# O–U phases

> O–U system: 21 phases (tier A 5, tier C 1, liquid 2, gas 2, needs_review 7, unresolved_no_candidates 4); 19 stable in a calculated diagram in the ORCHID phase registry, with names, structure type when the stored evidence supports an assignment under the stated tier rules, calculated stability, verbatim TDB PHASE/CONSTITUENT statements and example references.

HTML: https://data.orchid-project.org/phases/pages/O-U.html · Markdown: https://data.orchid-project.org/phases/pages/O-U.md

21 phases (tier A 5, tier C 1, liquid 2, gas 2, needs_review 7, unresolved_no_candidates 4); 19 stable in a calculated diagram. Structure types are assigned only when the stored evidence supports an assignment under the stated tier rules (tier A: standard phase name; tier B: unique Materials Project + OQMD on-hull match, DFT-supported; tier C: one structure stated by the assessment's crystallographic table, assessor-stated); other phases list candidates and are marked needs_review. Stability is from phase diagrams calculated with pycalphad from the SGTE binary collection (evidence class: model).

Data: [interactive registry](https://orchid-project.org/phases/?q=O-U) · [full JSON](https://data.orchid-project.org/phases/systems/O-U.json) · [O–U system page](https://data.orchid-project.org/systems/O-U.html) · [Markdown](https://data.orchid-project.org/phases/pages/O-U.md) · [field reference](https://data.orchid-project.org/phases/SCHEMA.md)

Table: Phases of the O–U system (21)

| Phase | Structure | Basis | Stability (calculated) | Literature values | TDB models |
|---|---|---|---|---:|---:|
| [ORTHORHOMBIC_A20](#phase-o-u-a20-orthorhombic); _phase:o-u:a20-orthorhombic_ | alpha-U · A20 · oC4 · Cmcm (63) | tier A: standard phase name | stable in 6 of 6 calculated diagram(s): 300–942.02 K, x(O) 0–0 | 0 | 6 |
| [BCC_A2](#phase-o-u-bcc-a2); _phase:o-u:bcc-a2_ | W · A2 · cI2 · Im-3m (229) | tier A: standard phase name | stable in 6 of 6 calculated diagram(s): 1048.99–3115.49 K, x(O) 0–0 | 0 | 6 |
| [FCC_A1](#phase-o-u-fcc-a1); _phase:o-u:fcc-a1_ | Cu · A1 · cF4 · Fm-3m (225) | tier A: standard phase name | not stable in 6 calculated diagram(s) | 0 | 6 |
| [GAS](#phase-o-u-gas); _phase:o-u:gas_ | gas | gas | stable in 6 of 6 calculated diagram(s): 300.54–4000 K, x(O) 0.45649–1 | 6 | 6 |
| [HCP_A3](#phase-o-u-hcp-a3); _phase:o-u:hcp-a3_ | Mg · A3 · hP2 · P6_3/mmc (194) | tier A: standard phase name | not stable in 6 calculated diagram(s) | 0 | 6 |
| [ION](#phase-o-u-ion); _phase:o-u:ion_ | liquid | liquid | stable in 2 of 2 calculated diagram(s): 1407.99–4001.27 K, x(O) 0–0.73055 | 0 | 2 |
| [LIQUID](#phase-o-u-liquid); _phase:o-u:liquid_ | liquid | liquid | stable in 4 of 6 calculated diagram(s): 1407.96–4000 K, x(O) 0–0.70746 | 175 | 6 |
| [O2GAS](#phase-o-u-o2gas); _phase:o-u:o2gas_ | gas | gas | stable in 6 of 6 calculated diagram(s): 300–1176.79 K, x(O) 1–1 | 0 | 6 |
| [TETRAGONAL_U](#phase-o-u-u-tetragonal); _phase:o-u:u-tetragonal_ |  | needs_review | stable in 6 of 6 calculated diagram(s): 942.02–1048.99 K, x(O) 0–0 | 0 | 6 |
| [U3O8](#phase-o-u-u3o8); _phase:o-u:u3o8_ |  | needs_review | stable in 4 of 4 calculated diagram(s): 300–2165.88 K, x(O) 0.72727–0.72727 | 19 | 4 |
| [U3O8_S1](#phase-o-u-u3o8-s1); _phase:o-u:u3o8-s1_ |  | needs_review | stable in 2 of 2 calculated diagram(s): 300–483 K, x(O) 0.72727–0.72727 | 0 | 2 |
| [U3O8_S2](#phase-o-u-u3o8-s2); _phase:o-u:u3o8-s2_ |  | needs_review | stable in 2 of 2 calculated diagram(s): 483–568 K, x(O) 0.72727–0.72727 | 0 | 2 |
| [U3O8_S3](#phase-o-u-u3o8-s3); _phase:o-u:u3o8-s3_ |  | needs_review | stable in 2 of 2 calculated diagram(s): 568–830 K, x(O) 0.72727–0.72727 | 0 | 2 |
| [U3O8_S4](#phase-o-u-u3o8-s4); _phase:o-u:u3o8-s4_ |  | unresolved_no_candidates | stable in 2 of 2 calculated diagram(s): 830–2034.43 K, x(O) 0.72727–0.72727 | 0 | 2 |
| [U4O9](#phase-o-u-u4o9); _phase:o-u:u4o9_ |  | unresolved_no_candidates | stable in 4 of 4 calculated diagram(s): 300–1703.75 K, x(O) 0.69231–0.69231 | 32 | 4 |
| [U4O9_S1](#phase-o-u-u4o9-s1); _phase:o-u:u4o9-s1_ |  | unresolved_no_candidates | stable in 2 of 2 calculated diagram(s): 300–348 K, x(O) 0.69231–0.69231 | 0 | 2 |
| [U4O9_S2](#phase-o-u-u4o9-s2); _phase:o-u:u4o9-s2_ |  | needs_review | stable in 2 of 2 calculated diagram(s): 348–850 K, x(O) 0.69231–0.69231 | 0 | 2 |
| [U4O9_S3](#phase-o-u-u4o9-s3); _phase:o-u:u4o9-s3_ |  | unresolved_no_candidates | stable in 2 of 2 calculated diagram(s): 849.97–1404.17 K, x(O) 0.69231–0.69231 | 0 | 2 |
| [UO2_C1](#phase-o-u-uo2-c1); _phase:o-u:uo2-c1_ | CaF2 · C1 · cF12 · Fm-3m (225) | tier A: standard phase name | stable in 6 of 6 calculated diagram(s): 300–3143.6 K, x(O) 0.62425–0.69355 | 206 | 6 |
| [UO2_WILD](#phase-o-u-uo2-wild); _phase:o-u:uo2-wild_ |  | needs_review | stable in 1 of 1 calculated diagram(s): 300.5–3140.2 K, x(O) 0.62404–0.69156 | 0 | 1 |
| [UO3](#phase-o-u-uo3); _phase:o-u:uo3_ | UO3 · oF128 · Fddd (70) | tier C: assessor-stated (Hallstedt 2025 crystallographic table) | stable in 6 of 6 calculated diagram(s): 300–941.79 K, x(O) 0.75–0.75 | 18 | 6 |

## ORTHORHOMBIC_A20 (O–U)

- Id: `phase:o-u:a20-orthorhombic`; status `assigned`
- Structure: alpha-U · A20 · oC4 · Cmcm (63); type `st:a20-alpha-u-oc4`; tier A: standard phase name; confidence high
- Stoichiometry: U 1.0000
- Stability: stable in 6 of 6 calculated diagram(s): 300–942.02 K, x(O) 0–0
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:a20-orthorhombic)

Names (7): _corpus: _corpus:phase:o-u:a20-orthorhombic  
_tdb: _tdb:UO-02Che.tdb:ORTHORHOMBIC_A20, tdb:UO-02Gue.tdb:ORTHORHOMBIC_A20, tdb:UO-04Che.tdb:ORTHORHOMBIC_A20, tdb:UO-08Bar.tdb:ORTHORHOMBIC_A20, tdb:UO-11Gue.tdb:ORTHORHOMBIC_A20, tdb:UO-23Jia.tdb:ORTHORHOMBIC_A20  


### TDB models of ORTHORHOMBIC_A20 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): ORTHORHOMBIC_A20, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
64: PHASE ORTHORHOMBIC_A20 % 1 1 !
65: CONST ORTHORHOMBIC_A20 : U : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): ORTHORHOMBIC_A20, type code %, sha256 `dabf96b4fc286974…`

~~~~text
63: PHASE ORTHORHOMBIC_A20 % 1 1 !
64: CONST ORTHORHOMBIC_A20 : U : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): ORTHORHOMBIC_A20, type code %, sha256 `c929e68af28f01b2…`

~~~~text
66: PHASE ORTHORHOMBIC_A20 % 1 1 !
67: CONST ORTHORHOMBIC_A20 : U : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): ORTHORHOMBIC_A20, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
66: PHASE ORTHORHOMBIC_A20 % 1 1 !
67: CONST ORTHORHOMBIC_A20 : U : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): ORTHORHOMBIC_A20, type code %, sha256 `880201adec5fc9b2…`

~~~~text
65: PHASE ORTHORHOMBIC_A20 % 1 1 !
66: CONST ORTHORHOMBIC_A20 : U : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): ORTHORHOMBIC_A20, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
68: PHASE ORTHORHOMBIC_A20 % 1 1 !
69: CONST ORTHORHOMBIC_A20 : U : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## BCC_A2 (O–U)

- Id: `phase:o-u:bcc-a2`; status `assigned`
- Structure: W · A2 · cI2 · Im-3m (229); type `st:a2-w-ci2`; tier A: standard phase name; confidence high
- Stoichiometry: U 1.0000
- Stability: stable in 6 of 6 calculated diagram(s): 1048.99–3115.49 K, x(O) 0–0
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:bcc-a2)

Names (7): _corpus: _corpus:phase:o-u:bcc-a2  
_tdb: _tdb:UO-02Che.tdb:BCC_A2, tdb:UO-02Gue.tdb:BCC_A2, tdb:UO-04Che.tdb:BCC_A2, tdb:UO-08Bar.tdb:BCC_A2, tdb:UO-11Gue.tdb:BCC_A2, tdb:UO-23Jia.tdb:BCC_A2  


### TDB models of BCC_A2 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): BCC_A2, type code %B, sha256 `f43d17d1669f4d07…`

~~~~text
54: PHASE BCC_A2 %B 2 1 3 !
55: CONST BCC_A2 : U : VA : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): BCC_A2, type code %B, sha256 `dabf96b4fc286974…`

~~~~text
53: PHASE BCC_A2 %B 2 1 3 !
54: CONST BCC_A2 : U : VA : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): BCC_A2, type code %B, sha256 `c929e68af28f01b2…`

~~~~text
56: PHASE BCC_A2 %B 2 1 3 !
57: CONST BCC_A2 : U : VA : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): BCC_A2, type code %B, sha256 `9c0bd45c36c212ad…`

~~~~text
56: PHASE BCC_A2 %B 2 1 3 !
57: CONST BCC_A2 : U : VA : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): BCC_A2, type code %B, sha256 `880201adec5fc9b2…`

~~~~text
55: PHASE BCC_A2 %B 2 1 3 !
56: CONST BCC_A2 : U : VA : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): BCC_A2, type code %B, sha256 `cdb48540c17b0ad4…`

~~~~text
58: PHASE BCC_A2 %B 2 1 3 !
59: CONST BCC_A2 : U : VA : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## FCC_A1 (O–U)

- Id: `phase:o-u:fcc-a1`; status `assigned`
- Structure: Cu · A1 · cF4 · Fm-3m (225); type `st:a1-cu-cf4`; tier A: standard phase name; confidence high
- Stability: not stable in 6 calculated diagram(s)
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:fcc-a1)

Names (7): _corpus: _corpus:phase:o-u:fcc-a1  
_tdb: _tdb:UO-02Che.tdb:FCC_A1, tdb:UO-02Gue.tdb:FCC_A1, tdb:UO-04Che.tdb:FCC_A1, tdb:UO-08Bar.tdb:FCC_A1, tdb:UO-11Gue.tdb:FCC_A1, tdb:UO-23Jia.tdb:FCC_A1  


### TDB models of FCC_A1 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): FCC_A1, type code %A, sha256 `f43d17d1669f4d07…`

~~~~text
49: PHASE FCC_A1 %A 2 1 1 !
50: CONST FCC_A1 : U : VA : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): FCC_A1, type code %A, sha256 `dabf96b4fc286974…`

~~~~text
48: PHASE FCC_A1 %A 2 1 1 !
49: CONST FCC_A1 : U : VA : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): FCC_A1, type code %A, sha256 `c929e68af28f01b2…`

~~~~text
51: PHASE FCC_A1 %A 2 1 1 !
52: CONST FCC_A1 : U : VA : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): FCC_A1, type code %A, sha256 `9c0bd45c36c212ad…`

~~~~text
51: PHASE FCC_A1 %A 2 1 1 !
52: CONST FCC_A1 : U : VA : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): FCC_A1, type code %A, sha256 `880201adec5fc9b2…`

~~~~text
50: PHASE FCC_A1 %A 2 1 1 !
51: CONST FCC_A1 : U : O VA% : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): FCC_A1, type code %A, sha256 `cdb48540c17b0ad4…`

~~~~text
53: PHASE FCC_A1 %A 2 1 1 !
54: CONST FCC_A1 : U : VA : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## GAS (O–U)

- Id: `phase:o-u:gas`; status `assigned`
- Structure: gas; type `st:gas`; gas; confidence high
- Stability: stable in 6 of 6 calculated diagram(s): 300.54–4000 K, x(O) 0.45649–1
- Literature: 6 values (6 accepted) from 1 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:gas)

Names (8): _corpus: _corpus:phase:o-u:gas  
_paper: _paper:10.1016/s0022-3115(02)00878-4:Gas  
_tdb: _tdb:UO-02Che.tdb:GAS, tdb:UO-02Gue.tdb:GAS, tdb:UO-04Che.tdb:GAS, tdb:UO-08Bar.tdb:GAS, tdb:UO-11Gue.tdb:GAS, tdb:UO-23Jia.tdb:GAS  


### TDB models of GAS (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): GAS, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
100: PHASE GAS:G % 1 1 !
101: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): GAS, type code %, sha256 `dabf96b4fc286974…`

~~~~text
119: PHASE GAS:G % 1 1 !
120: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): GAS, type code %, sha256 `c929e68af28f01b2…`

~~~~text
102: PHASE GAS:G % 1 1 !
103: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): GAS, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
102: PHASE GAS:G % 1 1 !
103: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): GAS, type code %, sha256 `880201adec5fc9b2…`

~~~~text
126: PHASE GAS:G % 1 1 !
127: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): GAS, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
104: PHASE GAS:G % 1 1 !
105: CONST GAS:G : O O2 O3 U UO UO2 UO3 : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_

## HCP_A3 (O–U)

- Id: `phase:o-u:hcp-a3`; status `assigned`
- Structure: Mg · A3 · hP2 · P6_3/mmc (194); type `st:a3-mg-hp2`; tier A: standard phase name; confidence high
- Stoichiometry: U 1.0000
- Stability: not stable in 6 calculated diagram(s)
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:hcp-a3)

Names (7): _corpus: _corpus:phase:o-u:hcp-a3  
_tdb: _tdb:UO-02Che.tdb:HCP_A3, tdb:UO-02Gue.tdb:HCP_A3, tdb:UO-04Che.tdb:HCP_A3, tdb:UO-08Bar.tdb:HCP_A3, tdb:UO-11Gue.tdb:HCP_A3, tdb:UO-23Jia.tdb:HCP_A3  


### TDB models of HCP_A3 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): HCP_A3, type code %A, sha256 `f43d17d1669f4d07…`

~~~~text
59: PHASE HCP_A3 %A 2 1 0.5 !
60: CONST HCP_A3 : U : VA : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): HCP_A3, type code %A, sha256 `dabf96b4fc286974…`

~~~~text
58: PHASE HCP_A3 %A 2 1 0.5 !
59: CONST HCP_A3 : U : VA : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): HCP_A3, type code %A, sha256 `c929e68af28f01b2…`

~~~~text
61: PHASE HCP_A3 %A 2 1 0.5 !
62: CONST HCP_A3 : U : VA : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): HCP_A3, type code %A, sha256 `9c0bd45c36c212ad…`

~~~~text
61: PHASE HCP_A3 %A 2 1 0.5 !
62: CONST HCP_A3 : U : VA : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): HCP_A3, type code %A, sha256 `880201adec5fc9b2…`

~~~~text
60: PHASE HCP_A3 %A 2 1 0.5 !
61: CONST HCP_A3 : U : VA : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): HCP_A3, type code %A, sha256 `cdb48540c17b0ad4…`

~~~~text
63: PHASE HCP_A3 %A 2 1 0.5 !
64: CONST HCP_A3 : U : VA : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## ION (O–U)

- Id: `phase:o-u:ion`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- Stability: stable in 2 of 2 calculated diagram(s): 1407.99–4001.27 K, x(O) 0–0.73055
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:ion)

Names (3): _corpus: _corpus:phase:o-u:ion  
_tdb: _tdb:UO-02Gue.tdb:ION, tdb:UO-11Gue.tdb:ION  


### TDB models of ION (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): ION, type code %, sha256 `dabf96b4fc286974…`

~~~~text
40: PHASE ION:Y % 2 1 1 !
41: CONST ION:Y : U+4 : O-2 VA O : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): ION, type code %, sha256 `880201adec5fc9b2…`

~~~~text
42: PHASE ION:Y % 2 1 1 !
43: CONST ION:Y : U+4 : O-2 VA O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## LIQUID (O–U)

- Id: `phase:o-u:liquid`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- Stability: stable in 4 of 6 calculated diagram(s): 1407.96–4000 K, x(O) 0–0.70746
- Literature: 175 values (175 accepted) from 3 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:liquid)

Names (12): _corpus: _corpus:phase:o-u:liquid  
_paper: _paper:10.1016/j.jnucmat.2008.02.003:L, paper:10.1016/j.jnucmat.2008.02.003:liquid, paper:10.1016/s0022-3115(02)00813-9:L1, paper:10.1016/s0022-3115(02)00813-9:L2, paper:10.1016/s0022-3115(02)00878-4:Liquid  
_tdb: _tdb:UO-02Che.tdb:LIQUID, tdb:UO-02Gue.tdb:LIQUID, tdb:UO-04Che.tdb:LIQUID, tdb:UO-08Bar.tdb:LIQUID, tdb:UO-11Gue.tdb:LIQUID, tdb:UO-23Jia.tdb:LIQUID  


### TDB models of LIQUID (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): LIQUID, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
44: PHASE LIQUID:L % 1 1 !
45: CONST LIQUID:L : O U UO2 : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): LIQUID, type code %, sha256 `dabf96b4fc286974…`

~~~~text
43: PHASE LIQUID:L % 1 1 !
44: CONST LIQUID:L : U : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): LIQUID, type code %, sha256 `c929e68af28f01b2…`

~~~~text
46: PHASE LIQUID:L % 1 1 !
47: CONST LIQUID:L : O U UO2 : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): LIQUID, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
46: PHASE LIQUID:L % 1 1 !
47: CONST LIQUID:L : O U UO2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): LIQUID, type code %, sha256 `880201adec5fc9b2…`

~~~~text
45: PHASE LIQUID:L % 1 1 !
46: CONST LIQUID:L : U : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): LIQUID, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
48: PHASE LIQUID:L % 1 1 !
49: CONST LIQUID:L : O U UO2 : !
~~~~

Example references (10 of 10; assessments first): 

- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/0022-3115(70)90100-5](https://doi.org/10.1016/0022-3115%2870%2990100-5) R.E. Latta, R.E. Fryxell, Determination of solidus-liquidus temperatures in the uo2 + x system (−0.50<x<0.20), Journal of Nuclear Materials 35, 195-210 (1970).  
_cited as the source of values for this phase_
- [doi:10.1016/j.jnucmat.2005.04.002](https://doi.org/10.1016/j.jnucmat.2005.04.002) D. Manara, C. Ronchi, M. Sheindlin, M. Lewis, M. Brykin, Melting of stoichiometric and hyperstoichiometric uranium dioxide, Journal of Nuclear Materials 342, 148-163 (2005).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(67)90207-3](https://doi.org/10.1016/0022-3115%2867%2990207-3) M.J. Bannister, Melting temperatures in the system uranium — Uranium dioxide, Journal of Nuclear Materials 24, 340-342 (1967).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(80)90287-1](https://doi.org/10.1016/0022-3115%2880%2990287-1) S.P. Garg, R.J. Ackermann, Solubility of oxygen in liquid uranium and the composition of the lower phase boundary of uranium dioxide at 1950 K, Journal of Nuclear Materials 88, 309-311 (1980).  
_cited as the source of values for this phase_

## O2GAS (O–U)

- Id: `phase:o-u:o2gas`; status `assigned`
- Structure: gas; type `st:gas`; gas; confidence high
- Stability: stable in 6 of 6 calculated diagram(s): 300–1176.79 K, x(O) 1–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:o2gas)

Names (7): _corpus: _corpus:phase:o-u:o2gas  
_tdb: _tdb:UO-02Che.tdb:O2GAS, tdb:UO-02Gue.tdb:O2GAS, tdb:UO-04Che.tdb:O2GAS, tdb:UO-08Bar.tdb:O2GAS, tdb:UO-11Gue.tdb:O2GAS, tdb:UO-23Jia.tdb:O2GAS  


### TDB models of O2GAS (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): O2GAS, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
97: PHASE O2GAS % 1 1 !
98: CONST O2GAS : O2 :!
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): O2GAS, type code %, sha256 `dabf96b4fc286974…`

~~~~text
116: PHASE O2GAS % 1 1 !
117: CONST O2GAS : O2 :!
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): O2GAS, type code %, sha256 `c929e68af28f01b2…`

~~~~text
99: PHASE O2GAS % 1 1 !
100: CONST O2GAS : O2 :!
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): O2GAS, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
99: PHASE O2GAS % 1 1 !
100: CONST O2GAS : O2 :!
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): O2GAS, type code %, sha256 `880201adec5fc9b2…`

~~~~text
123: PHASE O2GAS % 1 1 !
124: CONST O2GAS : O2 :!
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): O2GAS, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
101: PHASE O2GAS % 1 1 !
102: CONST O2GAS : O2 :!
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## TETRAGONAL_U (O–U)

- Id: `phase:o-u:u-tetragonal`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:TETRAGONAL; no_structure_token
- Candidate (sgte_mmc2): beta-U · A_b · tP30 · P4_2/mnm (136) — Hallstedt 2025 mmc2 row for TETRAGONAL_U: beta-U
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-02Che.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-02Gue.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-04Che.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-08Bar.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-11Gue.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — UO-23Jia.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
- Stoichiometry: U 1.0000
- Stability: stable in 6 of 6 calculated diagram(s): 942.02–1048.99 K, x(O) 0–0
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u-tetragonal)

Names (7): _corpus: _corpus:phase:o-u:u-tetragonal  
_tdb: _tdb:UO-02Che.tdb:TETRAGONAL_U, tdb:UO-02Gue.tdb:TETRAGONAL_U, tdb:UO-04Che.tdb:TETRAGONAL_U, tdb:UO-08Bar.tdb:TETRAGONAL_U, tdb:UO-11Gue.tdb:TETRAGONAL_U, tdb:UO-23Jia.tdb:TETRAGONAL_U  


### TDB models of TETRAGONAL_U (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): TETRAGONAL_U, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
69: PHASE TETRAGONAL_U % 1 1 !
70: CONST TETRAGONAL_U : U : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): TETRAGONAL_U, type code %, sha256 `dabf96b4fc286974…`

~~~~text
68: PHASE TETRAGONAL_U % 1 1 !
69: CONST TETRAGONAL_U : U : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): TETRAGONAL_U, type code %, sha256 `c929e68af28f01b2…`

~~~~text
71: PHASE TETRAGONAL_U % 1 1 !
72: CONST TETRAGONAL_U : U : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): TETRAGONAL_U, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
71: PHASE TETRAGONAL_U % 1 1 !
72: CONST TETRAGONAL_U : U : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): TETRAGONAL_U, type code %, sha256 `880201adec5fc9b2…`

~~~~text
70: PHASE TETRAGONAL_U % 1 1 !
71: CONST TETRAGONAL_U : U : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): TETRAGONAL_U, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
73: PHASE TETRAGONAL_U % 1 1 !
74: CONST TETRAGONAL_U : U : !
~~~~

Example references (6 of 6; assessments first): 

- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U3O8 (O–U)

- Id: `phase:o-u:u3o8`; status `needs_review`
- No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
- Candidate (dft_mp): P-62m (189) — on-hull MP U3O8 at x(U)=0.2727
- Candidate (tdb_comment): U3O8-ht2 · hP11 · P-62m — UO-02Che.tdb: 'Prototype U3O8-ht2 (hP11, P-62m) (S3)'
- Candidate (tdb_comment): alpha-U3O8 · oC22 · Amm2 — UO-02Che.tdb: 'Prototype alpha-U3O8 (oC22, Amm2) (S1)'
- Candidate (tdb_comment): beta-U3O8 · oC44 · Cmcm — UO-02Che.tdb: 'Prototype beta-U3O8 (oC44, Cmcm) (S2)'
- Candidate (tdb_comment): U3O8-ht2 · hP11 · P-62m — UO-04Che.tdb: 'Prototype U3O8-ht2 (hP11, P-62m) (S3)'
- Candidate (tdb_comment): alpha-U3O8 · oC22 · Amm2 — UO-04Che.tdb: 'Prototype alpha-U3O8 (oC22, Amm2) (S1)'
- Candidate (tdb_comment): beta-U3O8 · oC44 · Cmcm — UO-04Che.tdb: 'Prototype beta-U3O8 (oC44, Cmcm) (S2)'
- Candidate (tdb_comment): U3O8-ht2 · hP11 · P-62m — UO-08Bar.tdb: 'Prototype U3O8-ht2 (hP11, P-62m) (S3)'
- Stoichiometry: O 0.7273, U 0.2727
- Stability: stable in 4 of 4 calculated diagram(s): 300–2165.88 K, x(O) 0.72727–0.72727
- Literature: 19 values (19 accepted) from 1 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u3o8)

Names (7): _corpus: _corpus:phase:o-u:u3o8  
_paper: _paper:10.1016/s0022-3115(02)00813-9:U3O8, paper:10.1016/s0022-3115(02)00813-9:U3O8-z  
_tdb: _tdb:UO-02Che.tdb:U3O8, tdb:UO-04Che.tdb:U3O8, tdb:UO-08Bar.tdb:U3O8, tdb:UO-23Jia.tdb:U3O8  


### TDB models of U3O8 (4): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): U3O8, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
89: PHASE U3O8 % 2 3 8 !
90: CONST U3O8 : U : O : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): U3O8, type code %, sha256 `c929e68af28f01b2…`

~~~~text
91: PHASE U3O8 % 2 3 8 !
92: CONST U3O8 : U : O : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): U3O8, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
91: PHASE U3O8 % 2 3 8 !
92: CONST U3O8 : U : O : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): U3O8, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
93: PHASE U3O8 % 2 3 8 !
94: CONST U3O8 : U : O : !
~~~~

Example references (10 of 11; assessments first): 

- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1002/zaac.19120780119](https://doi.org/10.1002/zaac.19120780119) W. G. Mixter, Bildungswärmen der Oxyde von Vanadium und Uran, Z. Anorg. Chem. 78, 221-238 (1912).  
_cited as the source of values for this phase_
- [doi:10.1007/bf01489634](https://doi.org/10.1007/bf01489634) M. M. Popov, M. I. Ivanov, Heats of formation of PuO2 AND U3O8, The Soviet Journal of Atomic Energy 2, 439-443 (1957).  
_cited as the source of values for this phase_
- [doi:10.1016/0021-9614(69)90046-9](https://doi.org/10.1016/0021-9614%2869%2990046-9) Elmer J Huber, Charles E Holley, Enthalpies of formation of triuranium octaoxide and uranium dioxide, The Journal of Chemical Thermodynamics 1, 267-272 (1969).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-1902(61)80437-5](https://doi.org/10.1016/0022-1902%2861%2980437-5) L.E.J. Roberts, A.J. Walter, Equilibrium pressures and phase relations in the uranium oxide system, Journal of Inorganic and Nuclear Chemistry 22, 213-229 (1961).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(70)90157-1](https://doi.org/10.1016/0022-3115%2870%2990157-1) W. Van Lierde, J. Pelsmaekers, A. Lecocq-Robert, On the phase limits of U4O9, Journal of Nuclear Materials 37, 276-285 (1970).  
_cited as the source of values for this phase_
- [doi:10.1021/j150566a001](https://doi.org/10.1021/j150566a001) P. E. Blackburn, Oxygen Dissociation Pressures over Uranium Oxides, J. Phys. Chem. 62, 897-902 (1958).  
_cited as the source of values for this phase_

## U3O8_S1 (O–U)

- Id: `phase:o-u:u3o8-s1`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:S1; no_structure_token
- Candidate (sgte_mmc2): U3O8-alpha · oC22 · Amm2 (38) — Hallstedt 2025 mmc2 row for U3O8_S1: U3O8-alpha (structure uncertain)
- Candidate (tdb_comment): alpha-U3O8 · oC22 · Amm2 — UO-02Gue.tdb: 'Prototype alpha-U3O8 (oC22, Amm2)'
- Candidate (tdb_comment): alpha-U3O8 · oC22 · Amm2 — UO-11Gue.tdb: 'Prototype alpha-U3O8 (oC22, Amm2)'
- Stability: stable in 2 of 2 calculated diagram(s): 300–483 K, x(O) 0.72727–0.72727
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u3o8-s1)

Names (3): _corpus: _corpus:phase:o-u:u3o8-s1  
_tdb: _tdb:UO-02Gue.tdb:U3O8_S1, tdb:UO-11Gue.tdb:U3O8_S1  


### TDB models of U3O8_S1 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U3O8_S1, type code %, sha256 `dabf96b4fc286974…`

~~~~text
93: PHASE U3O8_S1:I % 2 3 8 !
94: CONST U3O8_S1:I : U+5 U+6 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U3O8_S1, type code %, sha256 `880201adec5fc9b2…`

~~~~text
100: PHASE U3O8_S1:I % 2 3 8 !
101: CONST U3O8_S1:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U3O8_S2 (O–U)

- Id: `phase:o-u:u3o8-s2`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:S2; no_structure_token
- Candidate (sgte_mmc2): U3O8-beta · oC44 · Cmcm (63) — Hallstedt 2025 mmc2 row for U3O8_S2: U3O8-beta (structure uncertain)
- Candidate (tdb_comment): beta-U3O8 · oC44 · Cmcm — UO-02Gue.tdb: 'Prototype beta-U3O8 (oC44, Cmcm)'
- Candidate (tdb_comment): beta-U3O8 · oC44 · Cmcm — UO-11Gue.tdb: 'Prototype beta-U3O8 (oC44, Cmcm)'
- Stability: stable in 2 of 2 calculated diagram(s): 483–568 K, x(O) 0.72727–0.72727
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u3o8-s2)

Names (3): _corpus: _corpus:phase:o-u:u3o8-s2  
_tdb: _tdb:UO-02Gue.tdb:U3O8_S2, tdb:UO-11Gue.tdb:U3O8_S2  


### TDB models of U3O8_S2 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U3O8_S2, type code %, sha256 `dabf96b4fc286974…`

~~~~text
98: PHASE U3O8_S2:I % 2 3 8 !
99: CONST U3O8_S2:I : U+5 U+6 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U3O8_S2, type code %, sha256 `880201adec5fc9b2…`

~~~~text
105: PHASE U3O8_S2:I % 2 3 8 !
106: CONST U3O8_S2:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U3O8_S3 (O–U)

- Id: `phase:o-u:u3o8-s3`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:S3; no_structure_token
- Candidate (sgte_mmc2): U3O8-ht2 · hP11 · P-62m (189) — Hallstedt 2025 mmc2 row for U3O8_S3: U3O8-ht2 (structure uncertain)
- Candidate (tdb_comment): U3O8-ht2 · hP11 · P-62m — UO-02Gue.tdb: 'Prototype U3O8-ht2 (hP11, P-62m)'
- Candidate (tdb_comment): U3O8-ht2 · hP11 · P-62m — UO-11Gue.tdb: 'Prototype U3O8-ht2 (hP11, P-62m)'
- Stability: stable in 2 of 2 calculated diagram(s): 568–830 K, x(O) 0.72727–0.72727
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u3o8-s3)

Names (3): _corpus: _corpus:phase:o-u:u3o8-s3  
_tdb: _tdb:UO-02Gue.tdb:U3O8_S3, tdb:UO-11Gue.tdb:U3O8_S3  


### TDB models of U3O8_S3 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U3O8_S3, type code %, sha256 `dabf96b4fc286974…`

~~~~text
103: PHASE U3O8_S3:I % 2 3 8 !
104: CONST U3O8_S3:I : U+5 U+6 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U3O8_S3, type code %, sha256 `880201adec5fc9b2…`

~~~~text
110: PHASE U3O8_S3:I % 2 3 8 !
111: CONST U3O8_S3:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U3O8_S4 (O–U)

- Id: `phase:o-u:u3o8-s4`; status `unresolved_no_candidates`
- No structure assigned. Why: name_has_descriptive_tokens:S4; no_structure_token
- Stability: stable in 2 of 2 calculated diagram(s): 830–2034.43 K, x(O) 0.72727–0.72727
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u3o8-s4)

Names (3): _corpus: _corpus:phase:o-u:u3o8-s4  
_tdb: _tdb:UO-02Gue.tdb:U3O8_S4, tdb:UO-11Gue.tdb:U3O8_S4  


### TDB models of U3O8_S4 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U3O8_S4, type code %, sha256 `dabf96b4fc286974…`

~~~~text
108: PHASE U3O8_S4:I % 2 3 8 !
109: CONST U3O8_S4:I : U+5 U+6 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U3O8_S4, type code %, sha256 `880201adec5fc9b2…`

~~~~text
115: PHASE U3O8_S4:I % 2 3 8 !
116: CONST U3O8_S4:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U4O9 (O–U)

- Id: `phase:o-u:u4o9`; status `unresolved_no_candidates`
- No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
- Stoichiometry: O 0.6923, U 0.3077
- Stability: stable in 4 of 4 calculated diagram(s): 300–1703.75 K, x(O) 0.69231–0.69231
- Literature: 32 values (32 accepted) from 1 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u4o9)

Names (8): _corpus: _corpus:phase:o-u:u4o9  
_paper: _paper:10.1016/s0022-3115(02)00813-9:U4O9, paper:10.1016/s0022-3115(02)00813-9:U4O9-y, paper:10.1016/s0022-3115(02)00813-9:U4O9±y  
_tdb: _tdb:UO-02Che.tdb:U4O9, tdb:UO-04Che.tdb:U4O9, tdb:UO-08Bar.tdb:U4O9, tdb:UO-23Jia.tdb:U4O9  


### TDB models of U4O9 (4): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): U4O9, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
81: PHASE U4O9 % 2 4 9 !
82: CONST U4O9 : U : O : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): U4O9, type code %, sha256 `c929e68af28f01b2…`

~~~~text
83: PHASE U4O9 % 2 4 9 !
84: CONST U4O9 : U : O : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): U4O9, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
83: PHASE U4O9 % 2 4 9 !
84: CONST U4O9 : U : O : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): U4O9, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
85: PHASE U4O9 % 2 4 9 !
86: CONST U4O9 : U : O : !
~~~~

Example references (10 of 13; assessments first): 

- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1021/j150566a001](https://doi.org/10.1021/j150566a001) P. E. Blackburn, Oxygen Dissociation Pressures over Uranium Oxides, J. Phys. Chem. 62, 897-902 (1958).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(70)90157-1](https://doi.org/10.1016/0022-3115%2870%2990157-1) W. Van Lierde, J. Pelsmaekers, A. Lecocq-Robert, On the phase limits of U4O9, Journal of Nuclear Materials 37, 276-285 (1970).  
_cited as the source of values for this phase_
- [doi:10.1016/0021-9614(72)90042-0](https://doi.org/10.1016/0021-9614%2872%2990042-0) A.C Macleod, Enthalpy of UO2.25 to 1600 K by drop calorimetry, The Journal of Chemical Thermodynamics 4, 699-708 (1972).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-1902(61)80437-5](https://doi.org/10.1016/0022-1902%2861%2980437-5) L.E.J. Roberts, A.J. Walter, Equilibrium pressures and phase relations in the uranium oxide system, Journal of Inorganic and Nuclear Chemistry 22, 213-229 (1961).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(81)90187-2](https://doi.org/10.1016/0022-3115%2881%2990187-2) C. Picard, P. Gerdanian, Etude thermodynamique du systeme uranium-oxygene a 1050°C, Journal of Nuclear Materials 99, 184-189 (1981).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3697(65)90061-2](https://doi.org/10.1016/0022-3697%2865%2990061-2) Kunihiro Gotoo, Keiji Naito, Study on U4O9—part I. An anomaly of the heat capacity near the room temperature, Journal of Physics and Chemistry of Solids 26, 1673-1677 (1965).  
_cited as the source of values for this phase_

## U4O9_S1 (O–U)

- Id: `phase:o-u:u4o9-s1`; status `unresolved_no_candidates`
- No structure assigned. Why: name_has_descriptive_tokens:S1; no_structure_token
- Stability: stable in 2 of 2 calculated diagram(s): 300–348 K, x(O) 0.69231–0.69231
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u4o9-s1)

Names (3): _corpus: _corpus:phase:o-u:u4o9-s1  
_tdb: _tdb:UO-02Gue.tdb:U4O9_S1, tdb:UO-11Gue.tdb:U4O9_S1  


### TDB models of U4O9_S1 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U4O9_S1, type code %, sha256 `dabf96b4fc286974…`

~~~~text
78: PHASE U4O9_S1:I % 2 4 9 !
79: CONST U4O9_S1:I : U+4 U+5 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U4O9_S1, type code %, sha256 `880201adec5fc9b2…`

~~~~text
85: PHASE U4O9_S1:I % 2 4 9 !
86: CONST U4O9_S1:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U4O9_S2 (O–U)

- Id: `phase:o-u:u4o9-s2`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:S2; no_structure_token
- Candidate (sgte_mmc2): U4O9-beta · cF76 · F-43m (216) — Hallstedt 2025 mmc2 row for U4O9_S2: U4O9-beta (structure uncertain)
- Stability: stable in 2 of 2 calculated diagram(s): 348–850 K, x(O) 0.69231–0.69231
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u4o9-s2)

Names (3): _corpus: _corpus:phase:o-u:u4o9-s2  
_tdb: _tdb:UO-02Gue.tdb:U4O9_S2, tdb:UO-11Gue.tdb:U4O9_S2  


### TDB models of U4O9_S2 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U4O9_S2, type code %, sha256 `dabf96b4fc286974…`

~~~~text
83: PHASE U4O9_S2:I % 2 4 9 !
84: CONST U4O9_S2:I : U+4 U+5 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U4O9_S2, type code %, sha256 `880201adec5fc9b2…`

~~~~text
90: PHASE U4O9_S2:I % 2 4 9 !
91: CONST U4O9_S2:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## U4O9_S3 (O–U)

- Id: `phase:o-u:u4o9-s3`; status `unresolved_no_candidates`
- No structure assigned. Why: name_has_descriptive_tokens:S3; no_structure_token
- Stability: stable in 2 of 2 calculated diagram(s): 849.97–1404.17 K, x(O) 0.69231–0.69231
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:u4o9-s3)

Names (3): _corpus: _corpus:phase:o-u:u4o9-s3  
_tdb: _tdb:UO-02Gue.tdb:U4O9_S3, tdb:UO-11Gue.tdb:U4O9_S3  


### TDB models of U4O9_S3 (2): PHASE and CONSTITUENT statements as written

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): U4O9_S3, type code %, sha256 `dabf96b4fc286974…`

~~~~text
88: PHASE U4O9_S3:I % 2 4 9 !
89: CONST U4O9_S3:I : U+4 U+5 : O-2 : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): U4O9_S3, type code %, sha256 `880201adec5fc9b2…`

~~~~text
95: PHASE U4O9_S3:I % 2 4 9 !
96: CONST U4O9_S3:I : U : O : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_

## UO2_C1 (O–U)

- Id: `phase:o-u:uo2-c1`; status `assigned`
- Structure: CaF2 · C1 · cF12 · Fm-3m (225); type `st:c1-caf2-cf12`; tier A: standard phase name; confidence high
- Stability: stable in 6 of 6 calculated diagram(s): 300–3143.6 K, x(O) 0.62425–0.69355
- Literature: 206 values (206 accepted) from 2 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:uo2-c1)

Names (12): _corpus: _corpus:phase:o-u:uo2-c1  
_paper: _paper:10.1016/j.jnucmat.2008.02.003:UO2+x, paper:10.1016/s0022-3115(02)00813-9:S, paper:10.1016/s0022-3115(02)00813-9:UO2+x, paper:10.1016/s0022-3115(02)00813-9:UO2-x, paper:10.1016/s0022-3115(02)00813-9:UO2±x  
_tdb: _tdb:UO-02Che.tdb:UO2_C1, tdb:UO-02Gue.tdb:UO2_C1, tdb:UO-04Che.tdb:UO2_C1, tdb:UO-08Bar.tdb:UO2_C1, tdb:UO-11Gue.tdb:UO2_C1, tdb:UO-23Jia.tdb:UO2_C1  


### TDB models of UO2_C1 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): UO2_C1, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
74: PHASE UO2_C1 % 3 1 2 1 !
75: CONST UO2_C1 : U : O VA : O VA : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): UO2_C1, type code %, sha256 `dabf96b4fc286974…`

~~~~text
73: PHASE UO2_C1:I % 3 1 2 1 !
74: CONST UO2_C1:I : U+3 U+4 U+6 : O-2 VA : O-2 VA : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): UO2_C1, type code %, sha256 `c929e68af28f01b2…`

~~~~text
76: PHASE UO2_C1 % 3 1 2 1 !
77: CONST UO2_C1 : U : O VA : O VA : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): UO2_C1, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
76: PHASE UO2_C1 % 3 1 2 1 !
77: CONST UO2_C1 : U : O VA : O VA : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): UO2_C1, type code %, sha256 `880201adec5fc9b2…`

~~~~text
75: PHASE UO2_C1:I % 3 1 2 1 !
76: CONST UO2_C1:I : U+3 U+4 U+5 : O-2 VA : O-2 VA : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): UO2_C1, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
78: PHASE UO2_C1 % 1 1 !
79: CONST UO2_C1 : U UO2 UO3 : !
~~~~

Example references (10 of 16; assessments first): 

- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase_
- [doi:10.1016/0022-3115(70)90100-5](https://doi.org/10.1016/0022-3115%2870%2990100-5) R.E. Latta, R.E. Fryxell, Determination of solidus-liquidus temperatures in the uo2 + x system (−0.50<x<0.20), Journal of Nuclear Materials 35, 195-210 (1970).  
_cited as the source of values for this phase_
- [doi:10.1016/j.jnucmat.2005.04.002](https://doi.org/10.1016/j.jnucmat.2005.04.002) D. Manara, C. Ronchi, M. Sheindlin, M. Lewis, M. Brykin, Melting of stoichiometric and hyperstoichiometric uranium dioxide, Journal of Nuclear Materials 342, 148-163 (2005).  
_cited as the source of values for this phase_
- [doi:10.1021/j100724a002](https://doi.org/10.1021/j100724a002) R. J. Ackermann, E. G. Rauh, M. S. Chandrasekharaiah, Thermodynamics study of the urania-uranium system, J. Phys. Chem. 73, 762-769 (1969).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-3115(70)90010-3](https://doi.org/10.1016/0022-3115%2870%2990010-3) M. Tetenbaum, P.D. Hunt, Total pressure of uranium-bearing species over oxygen-deficient urania, Journal of Nuclear Materials 34, 86-91 (1970).  
_cited as the source of values for this phase_

## UO2_WILD (O–U)

- Id: `phase:o-u:uo2-wild`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:WILD; no_structure_token
- Candidate (tdb_comment): CaF2 · cF12 · Fm-3m — UO-11Gue.tdb: 'Prototype CaF2 (cF12, Fm-3m)'
- Stability: stable in 1 of 1 calculated diagram(s): 300.5–3140.2 K, x(O) 0.62404–0.69156
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:uo2-wild)

Names (2): _corpus: _corpus:phase:o-u:uo2-wild  
_tdb: _tdb:UO-11Gue.tdb:UO2_WILD  


### TDB models of UO2_WILD (1): PHASE and CONSTITUENT statements as written

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): UO2_WILD, type code %, sha256 `880201adec5fc9b2…`

~~~~text
80: PHASE UO2_WILD:I % 3 1 2 1 !
81: CONST UO2_WILD:I : U+3 U+4 U+5 : O-2 VA : O-2 VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_

## UO3 (O–U)

- Id: `phase:o-u:uo3`; status `assigned`
- Structure: UO3 · oF128 · Fddd (70); type `st:uo3-of128`; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
- Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) [doi:10.1016/j.calphad.2025.102833](https://doi.org/10.1016/j.calphad.2025.102833)
- Caveat: not certain from the name or DFT alone (no_structure_token, off_stoichiometric_model); structure as stated in the SGTE crystallographic table for this phase name and system
- Stability: stable in 6 of 6 calculated diagram(s): 300–941.79 K, x(O) 0.75–0.75
- Literature: 18 values (18 accepted) from 2 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:o-u:uo3)

Names (9): _corpus: _corpus:phase:o-u:uo3  
_paper: _paper:10.1016/s0022-3115(02)00813-9:UO3, paper:10.1016/s0022-3115(02)00878-4:UO3  
_tdb: _tdb:UO-02Che.tdb:UO3, tdb:UO-02Gue.tdb:UO3, tdb:UO-04Che.tdb:UO3, tdb:UO-08Bar.tdb:UO3, tdb:UO-11Gue.tdb:UO3, tdb:UO-23Jia.tdb:UO3  


### TDB models of UO3 (6): PHASE and CONSTITUENT statements as written

[UO-02Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Che.tdb): UO3, type code %, sha256 `f43d17d1669f4d07…`

~~~~text
94: PHASE UO3 % 2 1 3 !
95: CONST UO3 : U : O : !
~~~~

[UO-02Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-02Gue.tdb): UO3, type code %, sha256 `dabf96b4fc286974…`

~~~~text
113: PHASE UO3:I % 2 1 3 !
114: CONST UO3:I : U+6 : O-2 : !
~~~~

[UO-04Che.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-04Che.tdb): UO3, type code %, sha256 `c929e68af28f01b2…`

~~~~text
96: PHASE UO3 % 2 1 3 !
97: CONST UO3 : U : O : !
~~~~

[UO-08Bar.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-08Bar.tdb): UO3, type code %, sha256 `9c0bd45c36c212ad…`

~~~~text
96: PHASE UO3 % 2 1 3 !
97: CONST UO3 : U : O : !
~~~~

[UO-11Gue.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-11Gue.tdb): UO3, type code %, sha256 `880201adec5fc9b2…`

~~~~text
120: PHASE UO3:I % 2 1 3 !
121: CONST UO3:I : U+6 : O-2 : !
~~~~

[UO-23Jia.tdb](https://orchid-project.org/data/databases/sgte-binary/UO-23Jia.tdb): UO3, type code %, sha256 `cdb48540c17b0ad4…`

~~~~text
98: PHASE UO3 % 2 1 3 !
99: CONST UO3 : U : O : !
~~~~

Example references (10 of 11; assessments first): 

- [doi:10.1016/S0022-3115(02)00813-9](https://doi.org/10.1016/S0022-3115%2802%2900813-9) P.-Y. Chevalier, E. Fischer, B. Cheynet, J. Nucl. Mater., 303, 1-28(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/S0022-3115(02)00878-4](https://doi.org/10.1016/S0022-3115%2802%2900878-4) C. Gueneau, M. Baichi, D. Labroche, C. Chatillon, B. Sundman, J. Nucl. Mater., 304, 161-75(2002).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/j.calphad.2004.03.005](https://doi.org/10.1016/j.calphad.2004.03.005) Pierre-Yves Chevalier, Evelyne Fischer, Bertrand Cheynet, Progress in the thermodynamic modelling of the O–U–Zr ternary system, Calphad 28, 15-40 (2004).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2008.02.003](https://doi.org/10.1016/j.jnucmat.2008.02.003) M. Barrachin, P.Y. Chevalier, B. Cheynet, E. Fischer, New modelling of the U–O–Zr phase diagram in the hyper-stoichiometric region and consequences for the fuel rod liquefaction in oxidising conditions, Journal of Nuclear Materials 375, 397-409 (2008).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2011.07.033](https://doi.org/10.1016/j.jnucmat.2011.07.033) Christine Guéneau, Nathalie Dupin, Bo Sundman, Chantal Martial, Jean-Christophe Dumas, Stéphane Gossé et al., Thermodynamic modelling of advanced oxide and carbide nuclear fuels: Description of the U–Pu–O–C systems, Journal of Nuclear Materials 419, 145-167 (2011).  
_assessment that models this phase_
- [doi:10.1016/j.jnucmat.2022.154180](https://doi.org/10.1016/j.jnucmat.2022.154180) Yueshan Jiang, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang, Xiaogang Lu, Thermodynamic analysis for molten corium stratification with U-Zr-O-Fe database, Journal of Nuclear Materials 574, 154180 (2023).  
_assessment that models this phase_
- [doi:10.1039/tf9656100050](https://doi.org/10.1039/tf9656100050) E. H. P. Cordfunke, P. Aling, System UO3+ U3O8: dissociation pressure of ?-UO3, Trans. Faraday Soc. 61, 50 (1965).  
_cited as the source of values for this phase_
- [doi:10.1002/zaac.19120780119](https://doi.org/10.1002/zaac.19120780119) W. G. Mixter, Bildungswärmen der Oxyde von Vanadium und Uran, Z. Anorg. Chem. 78, 221-238 (1912).  
_cited as the source of values for this phase_
- [doi:10.1016/0021-9614(78)90046-0](https://doi.org/10.1016/0021-9614%2878%2990046-0) Gerald K. Johnson, P.A.G. O'Hare, Thermochemistry of uranium compounds XI. Standard enthalpy of formation of γ-UO3, The Journal of Chemical Thermodynamics 10, 577-580 (1978).  
_cited as the source of values for this phase_
- [doi:10.1021/je60032a039](https://doi.org/10.1021/je60032a039) George C. Fitzgibbon, Daniel Pavone, Charles E. Holley, Enthalpies of solution and formation of some uranium oxides, J. Chem. Eng. Data 12, 122-125 (1967).  
_cited as the source of values for this phase_

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Registry: phase registry of binary systems (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735970
- R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065

Also cite B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file; A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work).

Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

```bibtex
@misc{orchid_phase_registry_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Registry: phase registry of binary systems}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735970},
  url       = {https://doi.org/10.5281/zenodo.23735970},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}
```

---

Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite the ORCHID phase registry and the sources named on the page (TDB assessments, Hallstedt 2025, Materials Project, OQMD). TDB statements are quoted as written; parameter expressions are not reproduced. Field reference: [SCHEMA.md](https://data.orchid-project.org/phases/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt).