O–Pu phases

14 phases (tier A 6, liquid 2, gas 2, needs_review 4); 10 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 · full JSON · O–Pu system page · Markdown · field reference

Phases of the O–Pu system (14)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
TETRAGONAL_A6 phase:o-pu:a6-tetragonal	In · A6 · tI2 · I4/mmm (139)	tier A: standard phase name	not stable in 3 calculated diagram(s)	2	3
BCC_A2 phase:o-pu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 3 calculated diagram(s): 912–913 K, x(O) 0–0	2	3
FCC_A1 phase:o-pu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 3 calculated diagram(s)	0	3
GAS phase:o-pu:gas	gas	gas	stable in 3 of 3 calculated diagram(s): 300.29–4000 K, x(O) 1e-05–1	3	3
ION phase:o-pu:ion	liquid	liquid	stable in 3 of 3 calculated diagram(s): 912–4000 K, x(O) 0–0.6682	0	3
LIQUID phase:o-pu:liquid	liquid	liquid	not stable in 3 calculated diagram(s)	19	3
O2GAS phase:o-pu:o2gas	gas	gas	stable in 3 of 3 calculated diagram(s): 300–1185 K, x(O) 1–1	0	3
ALPHA_PU phase:o-pu:pu-alpha		needs_review	stable in 3 of 3 calculated diagram(s): 300–405 K, x(O) 0–0	0	3
BETA_PU phase:o-pu:pu-beta		needs_review	stable in 1 of 3 calculated diagram(s): 397.62–462.62 K, x(O) 0–0	0	3
GAMMA_PU phase:o-pu:pu-gamma		needs_review	not stable in 3 calculated diagram(s)	0	3
PU2O3_D52 phase:o-pu:pu2o3-d52	A-La2O3 · D5_2 · hP5 · P-3m1 (164)	tier A: standard phase name	stable in 3 of 3 calculated diagram(s): 300–462.62 K, x(O) 0.6–0.6	33	3
PUO152_D53 phase:o-pu:puo152-d53		needs_review	stable in 3 of 3 calculated diagram(s): 300–737.47 K, x(O) 0.60317–0.60317	11	3
PUO161_D53 phase:o-pu:puo161-d53	Mn2O3 · D5_3 · cI80 · Ia-3 (206)	tier A: standard phase name	stable in 3 of 3 calculated diagram(s): 572.47–1444.76 K, x(O) 0.61717–0.63212	21	3
PUO2_C1 phase:o-pu:puo2-c1	CaF2 · C1 · cF12 · Fm-3m (225)	tier A: standard phase name	stable in 3 of 3 calculated diagram(s): 300–3043.58 K, x(O) 0.62007–0.66667	38	3

TETRAGONAL_A6 (O–Pu)

Id: phase:o-pu:a6-tetragonal; status assigned
Structure: In · A6 · tI2 · I4/mmm (139); type st:a6-in-ti2; tier A: standard phase name; confidence high
Stoichiometry: Pu 1.0000
Stability: not stable in 3 calculated diagram(s)
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:a6-tetragonal
paper: paper:10.1016/j.jnucmat.2008.06.013:δ′-Pu
tdb: tdb:PuO-08Gue.tdb:TETRAGONAL_A6, tdb:PuO-11Gue.tdb:TETRAGONAL_A6, tdb:PuO-23Fou.tdb:TETRAGONAL_A6

TDB models of TETRAGONAL_A6 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: TETRAGONAL_A6, type code %, sha256 8750a98340781a5d…

54: PHASE TETRAGONAL_A6 % 1 1 !
55: CONST TETRAGONAL_A6 : PU : !

PuO-11Gue.tdb: TETRAGONAL_A6, type code %, sha256 15a7df38baf15590…

60: PHASE TETRAGONAL_A6 % 1 1 !
61: CONST TETRAGONAL_A6 : PU : !

PuO-23Fou.tdb: TETRAGONAL_A6, type code %, sha256 fa82e84a7efa7216…

66: PHASE TETRAGONAL_A6 % 1 1 !
67: CONST TETRAGONAL_A6 : PU : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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

BCC_A2 (O–Pu)

Id: phase:o-pu:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: Pu 1.0000
Stability: stable in 1 of 3 calculated diagram(s): 912–913 K, x(O) 0–0
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:bcc-a2
paper: paper:10.1016/j.jnucmat.2008.06.013:ε-Pu
tdb: tdb:PuO-08Gue.tdb:BCC_A2, tdb:PuO-11Gue.tdb:BCC_A2, tdb:PuO-23Fou.tdb:BCC_A2

TDB models of BCC_A2 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: BCC_A2, type code %B, sha256 8750a98340781a5d…

49: PHASE BCC_A2 %B 2 1 3 !
50: CONST BCC_A2 : PU : VA : !

PuO-11Gue.tdb: BCC_A2, type code %B, sha256 15a7df38baf15590…

55: PHASE BCC_A2 %B 2 1 3 !
56: CONST BCC_A2 : PU : VA : !

PuO-23Fou.tdb: BCC_A2, type code %B, sha256 fa82e84a7efa7216…

61: PHASE BCC_A2 %B 2 1 3 !
62: CONST BCC_A2 : PU : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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

FCC_A1 (O–Pu)

Id: phase:o-pu: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 3 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:fcc-a1
tdb: tdb:PuO-08Gue.tdb:FCC_A1, tdb:PuO-11Gue.tdb:FCC_A1, tdb:PuO-23Fou.tdb:FCC_A1

TDB models of FCC_A1 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: FCC_A1, type code %A, sha256 8750a98340781a5d…

44: PHASE FCC_A1 %A 2 1 1 !
45: CONST FCC_A1 : PU : VA : !

PuO-11Gue.tdb: FCC_A1, type code %A, sha256 15a7df38baf15590…

50: PHASE FCC_A1 %A 2 1 1 !
51: CONST FCC_A1 : PU : O VA% : !

PuO-23Fou.tdb: FCC_A1, type code %A, sha256 fa82e84a7efa7216…

56: PHASE FCC_A1 %A 2 1 1 !
57: CONST FCC_A1 : PU : O VA% : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

GAS (O–Pu)

Id: phase:o-pu:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 3 of 3 calculated diagram(s): 300.29–4000 K, x(O) 1e-05–1
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:gas
paper: paper:10.1016/j.jnucmat.2008.06.013:G
tdb: tdb:PuO-08Gue.tdb:GAS, tdb:PuO-11Gue.tdb:GAS, tdb:PuO-23Fou.tdb:GAS

TDB models of GAS (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: GAS, type code %, sha256 8750a98340781a5d…

95: PHASE GAS:G % 1 1 !
96: CONST GAS:G : O O2 O3 PU PUO PUO2 : !

PuO-11Gue.tdb: GAS, type code %, sha256 15a7df38baf15590…

101: PHASE GAS:G % 1 1 !
102: CONST GAS:G : O O2 O3 PU PUO PUO2 : !

PuO-23Fou.tdb: GAS, type code %, sha256 fa82e84a7efa7216…

107: PHASE GAS:G % 1 1 !
108: CONST GAS:G : O O2 O3 PU PUO PUO2 : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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

ION (O–Pu)

Id: phase:o-pu:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 3 of 3 calculated diagram(s): 912–4000 K, x(O) 0–0.6682
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:ion
tdb: tdb:PuO-08Gue.tdb:ION, tdb:PuO-11Gue.tdb:ION, tdb:PuO-23Fou.tdb:ION

TDB models of ION (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: ION, type code %, sha256 8750a98340781a5d…

36: PHASE ION:Y % 2 1 1 !
37: CONST ION:Y : PU+3 : O-2 VA O PUO2 : !

PuO-11Gue.tdb: ION, type code %, sha256 15a7df38baf15590…

42: PHASE ION:Y % 2 1 1 !
43: CONST ION:Y : PU+3 : O-2 VA O PUO2 : !

PuO-23Fou.tdb: ION, type code %, sha256 fa82e84a7efa7216…

48: PHASE ION:Y % 2 1 1 !
49: CONST ION:Y : PU+3 : O-2 VA O PUO2 : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

LIQUID (O–Pu)

Id: phase:o-pu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stoichiometry: Pu 1.0000
Stability: not stable in 3 calculated diagram(s)
Literature: 19 values (19 accepted) from 1 papers
Interactive: phase registry entry

Names (6): corpus: corpus:phase:o-pu:liquid
paper: paper:10.1016/j.jnucmat.2008.06.013:L, paper:10.1016/j.jnucmat.2008.06.013:L2
tdb: tdb:PuO-08Gue.tdb:LIQUID, tdb:PuO-11Gue.tdb:LIQUID, tdb:PuO-23Fou.tdb:LIQUID

TDB models of LIQUID (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: LIQUID, type code %, sha256 8750a98340781a5d…

39: PHASE LIQUID:L % 1 1 !
40: CONST LIQUID:L : PU : !

PuO-11Gue.tdb: LIQUID, type code %, sha256 15a7df38baf15590…

45: PHASE LIQUID:L % 1 1 !
46: CONST LIQUID:L : PU : !

PuO-23Fou.tdb: LIQUID, type code %, sha256 fa82e84a7efa7216…

51: PHASE LIQUID:L % 1 1 !
52: CONST LIQUID:L : PU : !

Example references (5 of 5; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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:10.1007/bf02841705 H. A. Wriedt, The O-Pu (Oxygen-Plutonium) system, Bulletin of Alloy Phase Diagrams 11, 184-202 (1990).
cited as the source of values for this phase
doi:10.1016/0022-3115(64)90132-1 T.D. Chikalla, C.E. McNeilly, R.E. Skavdahl, The plutonium-oxygen system, Journal of Nuclear Materials 12, 131-141 (1964).
cited as the source of values for this phase

O2GAS (O–Pu)

Id: phase:o-pu:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 3 of 3 calculated diagram(s): 300–1185 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:o2gas
tdb: tdb:PuO-08Gue.tdb:O2GAS, tdb:PuO-11Gue.tdb:O2GAS, tdb:PuO-23Fou.tdb:O2GAS

TDB models of O2GAS (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: O2GAS, type code %, sha256 8750a98340781a5d…

92: PHASE O2GAS % 1 1 !
93: CONST O2GAS : O2 :!

PuO-11Gue.tdb: O2GAS, type code %, sha256 15a7df38baf15590…

98: PHASE O2GAS % 1 1 !
99: CONST O2GAS : O2 :!

PuO-23Fou.tdb: O2GAS, type code %, sha256 fa82e84a7efa7216…

104: PHASE O2GAS % 1 1 !
105: CONST O2GAS : O2 :!

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

ALPHA_PU (O–Pu)

Id: phase:o-pu:pu-alpha; status needs_review
No structure assigned. Why: no_structure_token; unary_composition
Candidate (sgte_mmc2): alpha-Pu · mP16 · P2_1/m (11) — Hallstedt 2025 mmc2 row for ALPHA_PU: Pu (alpha)
Candidate (tdb_comment): alpha-Pu · mP16 · P2_1/m — PuO-08Gue.tdb: 'Prototype alpha-Pu (mP16, P2_1/m)'
Candidate (tdb_comment): alpha-Pu · mP16 · P2_1/m — PuO-11Gue.tdb: 'Prototype alpha-Pu (mP16, P2_1/m)'
Candidate (tdb_comment): alpha-Pu · mP16 · P2_1/m — PuO-23Fou.tdb: 'Prototype alpha-Pu (mP16, P2_1/m)'
Stoichiometry: Pu 1.0000
Stability: stable in 3 of 3 calculated diagram(s): 300–405 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:pu-alpha
tdb: tdb:PuO-08Gue.tdb:ALPHA_PU, tdb:PuO-11Gue.tdb:ALPHA_PU, tdb:PuO-23Fou.tdb:ALPHA_PU

TDB models of ALPHA_PU (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: ALPHA_PU, type code %, sha256 8750a98340781a5d…

59: PHASE ALPHA_PU % 1 1 !
60: CONST ALPHA_PU : PU : !

PuO-11Gue.tdb: ALPHA_PU, type code %, sha256 15a7df38baf15590…

65: PHASE ALPHA_PU % 1 1 !
66: CONST ALPHA_PU : PU : !

PuO-23Fou.tdb: ALPHA_PU, type code %, sha256 fa82e84a7efa7216…

71: PHASE ALPHA_PU % 1 1 !
72: CONST ALPHA_PU : PU : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

BETA_PU (O–Pu)

Id: phase:o-pu:pu-beta; status needs_review
No structure assigned. Why: no_structure_token; unary_composition
Candidate (sgte_mmc2): beta-Pu · mC34 · C2/m (12) — Hallstedt 2025 mmc2 row for BETA_PU: Pu (beta)
Candidate (tdb_comment): beta-Pu · mC34 · C2/m — PuO-08Gue.tdb: 'Prototype beta-Pu (mC34, C2/m)'
Candidate (tdb_comment): beta-Pu · mC34 · C2/m — PuO-11Gue.tdb: 'Prototype beta-Pu (mC34, C2/m)'
Candidate (tdb_comment): beta-Pu · mC34 · C2/m — PuO-23Fou.tdb: 'Prototype beta-Pu (mC34, C2/m)'
Stoichiometry: Pu 1.0000
Stability: stable in 1 of 3 calculated diagram(s): 397.62–462.62 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:pu-beta
tdb: tdb:PuO-08Gue.tdb:BETA_PU, tdb:PuO-11Gue.tdb:BETA_PU, tdb:PuO-23Fou.tdb:BETA_PU

TDB models of BETA_PU (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: BETA_PU, type code %, sha256 8750a98340781a5d…

64: PHASE BETA_PU % 1 1 !
65: CONST BETA_PU : PU : !

PuO-11Gue.tdb: BETA_PU, type code %, sha256 15a7df38baf15590…

70: PHASE BETA_PU % 1 1 !
71: CONST BETA_PU : PU : !

PuO-23Fou.tdb: BETA_PU, type code %, sha256 fa82e84a7efa7216…

76: PHASE BETA_PU % 1 1 !
77: CONST BETA_PU : PU : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

GAMMA_PU (O–Pu)

Id: phase:o-pu:pu-gamma; status needs_review
No structure assigned. Why: no_structure_token; unary_composition
Candidate (sgte_mmc2): gamma-Pu · oF8 · Fddd (70) — Hallstedt 2025 mmc2 row for GAMMA_PU: Hg4In, Pu (gamma)
Candidate (tdb_comment): gamma-Pu · oF8 · Fddd — PuO-08Gue.tdb: 'Prototype gamma-Pu (oF8, Fddd)'
Candidate (tdb_comment): gamma-Pu · oF8 · Fddd — PuO-11Gue.tdb: 'Prototype gamma-Pu (oF8, Fddd)'
Candidate (tdb_comment): gamma-Pu · oF8 · Fddd — PuO-23Fou.tdb: 'Prototype gamma-Pu (oF8, Fddd)'
Stoichiometry: Pu 1.0000
Stability: not stable in 3 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:o-pu:pu-gamma
tdb: tdb:PuO-08Gue.tdb:GAMMA_PU, tdb:PuO-11Gue.tdb:GAMMA_PU, tdb:PuO-23Fou.tdb:GAMMA_PU

TDB models of GAMMA_PU (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: GAMMA_PU, type code %, sha256 8750a98340781a5d…

69: PHASE GAMMA_PU % 1 1 !
70: CONST GAMMA_PU : PU : !

PuO-11Gue.tdb: GAMMA_PU, type code %, sha256 15a7df38baf15590…

75: PHASE GAMMA_PU % 1 1 !
76: CONST GAMMA_PU : PU : !

PuO-23Fou.tdb: GAMMA_PU, type code %, sha256 fa82e84a7efa7216…

81: PHASE GAMMA_PU % 1 1 !
82: CONST GAMMA_PU : PU : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase
doi: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

PU2O3_D52 (O–Pu)

Id: phase:o-pu:pu2o3-d52; status assigned
Structure: A-La2O3 · D5_2 · hP5 · P-3m1 (164); type st:d5-2-a-la2o3-hp5; tier A: standard phase name; confidence high
Stability: stable in 3 of 3 calculated diagram(s): 300–462.62 K, x(O) 0.6–0.6
Literature: 33 values (33 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:pu2o3-d52
paper: paper:10.1016/j.jnucmat.2008.06.013:Pu2O3
tdb: tdb:PuO-08Gue.tdb:PU2O3_D52, tdb:PuO-11Gue.tdb:PU2O3_D52, tdb:PuO-23Fou.tdb:PU2O3_D52

TDB models of PU2O3_D52 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: PU2O3_D52, type code %, sha256 8750a98340781a5d…

74: PHASE PU2O3_D52:I % 2 2 3 !
75: CONST PU2O3_D52:I : PU+3 : O-2 : !

PuO-11Gue.tdb: PU2O3_D52, type code %, sha256 15a7df38baf15590…

80: PHASE PU2O3_D52:I % 2 2 3 !
81: CONST PU2O3_D52:I : PU+3 : O-2 : !

PuO-23Fou.tdb: PU2O3_D52, type code %, sha256 fa82e84a7efa7216…

86: PHASE PU2O3_D52:I % 2 2 3 !
87: CONST PU2O3_D52:I : PU+3 : O-2 : !

Example references (10 of 10; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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:10.1007/bf02841705 H. A. Wriedt, The O-Pu (Oxygen-Plutonium) system, Bulletin of Alloy Phase Diagrams 11, 184-202 (1990).
cited as the source of values for this phase
doi:10.1016/0021-9614(77)90040-4 Pierre Chereau, Guy Déan, Michel De Franco, Paul Gerdanian, High-temperature microcalorimetric measurements of partial molar enthalpy of solution, ΔH(O2), in plutonium + oxygen, The Journal of Chemical Thermodynamics 9, 211-219 (1977).
cited as the source of values for this phase
doi:10.1016/0022-3115(87)90289-3 T.M. Besmann, Phase equilibria and thermodynamics of the Pu-O system: 1400 K to 1610 K, Journal of Nuclear Materials 144, 141-150 (1987).
cited as the source of values for this phase
doi:10.1063/1.441691 Howard E. Flotow, Marvin Tetenbaum, Heat capacity and thermodynamic functions of β-242Pu2O3 from 8 to 350 K. Contributions to the excess entropy, The Journal of Chemical Physics 74, 5269-5277 (1981).
cited as the source of values for this phase
doi:10.1016/0022-1902(65)80259-7 E.R. Gardner, T.L. Markin, R.S. Street, The plutonium-oxygen phase diagram, Journal of Inorganic and Nuclear Chemistry 27, 541-551 (1965).
cited as the source of values for this phase
doi:10.1016/0022-3115(64)90132-1 T.D. Chikalla, C.E. McNeilly, R.E. Skavdahl, The plutonium-oxygen system, Journal of Nuclear Materials 12, 131-141 (1964).
cited as the source of values for this phase
doi:10.1016/0022-3115(76)90114-8 Jean-Claude Boivineau, Etude par rayons x du diagramme plutonium-oxygene de la temperature ambiante jusqu'a 1100°c, Journal of Nuclear Materials 60, 31-38 (1976).
cited as the source of values for this phase

PUO152_D53 (O–Pu)

Id: phase:o-pu:puo152-d53; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:stoichiometry_contradicts_D5_3; stoichiometry_contradicts_D5_3:PuO-08Gue.tdb; stoichiometry_contradicts_D5_3:PuO-11Gue.tdb; stoichiometry_contradicts_D5_3:PuO-23Fou.tdb
Candidate (literature_printed): Mn2O3 · cI80 — printed with a label mapped to this phase
Candidate (name_token): Mn2O3 · D5_3 · cI80 · Ia-3 (206) — Strukturbericht/word 'D53' in the TDB name
Candidate (sgte_mmc2): Mn2O3 · D5_3 · cI80 · Ia-3 (206) — Hallstedt 2025 mmc2 row for PUO152_D53: PuO1.52
Candidate (tdb_comment): Mn2O3 · cI80 · Ia-3 — PuO-08Gue.tdb: 'Prototype Mn2O3 (cI80, Ia-3)'
Candidate (tdb_comment): Mn2O3 · cI80 · Ia-3 — PuO-11Gue.tdb: 'Prototype Mn2O3 (cI80, Ia-3)'
Candidate (tdb_comment): Mn2O3 · cI80 · Ia-3 — PuO-23Fou.tdb: 'Prototype Mn2O3 (cI80, Ia-3)'
Stoichiometry: O 0.6032, Pu 0.3968
Stability: stable in 3 of 3 calculated diagram(s): 300–737.47 K, x(O) 0.60317–0.60317
Literature: 11 values (11 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:puo152-d53
paper: paper:10.1016/j.jnucmat.2008.06.013:PuO1.52
tdb: tdb:PuO-08Gue.tdb:PUO152_D53, tdb:PuO-11Gue.tdb:PUO152_D53, tdb:PuO-23Fou.tdb:PUO152_D53

TDB models of PUO152_D53 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: PUO152_D53, type code %, sha256 8750a98340781a5d…

79: PHASE PUO152_D53 % 2 1 1.52 !
80: CONST PUO152_D53 : PU : O : !

PuO-11Gue.tdb: PUO152_D53, type code %, sha256 15a7df38baf15590…

85: PHASE PUO152_D53 % 2 1 1.52 !
86: CONST PUO152_D53 : PU : O : !

PuO-23Fou.tdb: PUO152_D53, type code %, sha256 fa82e84a7efa7216…

91: PHASE PUO152_D53 % 2 1 1.52 !
92: CONST PUO152_D53 : PU : O : !

Example references (7 of 7; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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:10.1007/bf02841705 H. A. Wriedt, The O-Pu (Oxygen-Plutonium) system, Bulletin of Alloy Phase Diagrams 11, 184-202 (1990).
cited as the source of values for this phase
doi:10.1016/0022-1902(65)80259-7 E.R. Gardner, T.L. Markin, R.S. Street, The plutonium-oxygen phase diagram, Journal of Inorganic and Nuclear Chemistry 27, 541-551 (1965).
cited as the source of values for this phase
doi:10.1016/0022-3115(76)90114-8 Jean-Claude Boivineau, Etude par rayons x du diagramme plutonium-oxygene de la temperature ambiante jusqu'a 1100°c, Journal of Nuclear Materials 60, 31-38 (1976).
cited as the source of values for this phase
doi:10.1016/0022-3115(64)90132-1 T.D. Chikalla, C.E. McNeilly, R.E. Skavdahl, The plutonium-oxygen system, Journal of Nuclear Materials 12, 131-141 (1964).
cited as the source of values for this phase

PUO161_D53 (O–Pu)

Id: phase:o-pu:puo161-d53; status assigned
Structure: Mn2O3 · D5_3 · cI80 · Ia-3 (206); type st:d5-3-mn2o3-ci80; tier A: standard phase name; confidence high
Stability: stable in 3 of 3 calculated diagram(s): 572.47–1444.76 K, x(O) 0.61717–0.63212
Literature: 21 values (21 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:o-pu:puo161-d53
paper: paper:10.1016/j.jnucmat.2008.06.013:PuO1.61
tdb: tdb:PuO-08Gue.tdb:PUO161_D53, tdb:PuO-11Gue.tdb:PUO161_D53, tdb:PuO-23Fou.tdb:PUO161_D53

TDB models of PUO161_D53 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: PUO161_D53, type code %, sha256 8750a98340781a5d…

84: PHASE PUO161_D53:I % 3 2 3 1 !
85: CONST PUO161_D53:I : PU+3 PU+4 : O-2 : O-2 VA : !

PuO-11Gue.tdb: PUO161_D53, type code %, sha256 15a7df38baf15590…

90: PHASE PUO161_D53:I % 3 2 3 1 !
91: CONST PUO161_D53:I : PU+3 PU+4 : O-2 : O-2 VA : !

PuO-23Fou.tdb: PUO161_D53, type code %, sha256 fa82e84a7efa7216…

96: PHASE PUO161_D53:I % 3 2 3 1 !
97: CONST PUO161_D53:I : PU+3 PU+4 : O-2 : O-2 VA : !

Example references (8 of 8; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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:10.1007/bf02841705 H. A. Wriedt, The O-Pu (Oxygen-Plutonium) system, Bulletin of Alloy Phase Diagrams 11, 184-202 (1990).
cited as the source of values for this phase
doi:10.1016/0022-3115(76)90114-8 Jean-Claude Boivineau, Etude par rayons x du diagramme plutonium-oxygene de la temperature ambiante jusqu'a 1100°c, Journal of Nuclear Materials 60, 31-38 (1976).
cited as the source of values for this phase
doi:10.1016/0022-1902(65)80259-7 E.R. Gardner, T.L. Markin, R.S. Street, The plutonium-oxygen phase diagram, Journal of Inorganic and Nuclear Chemistry 27, 541-551 (1965).
cited as the source of values for this phase
doi:10.1016/0022-3115(87)90289-3 T.M. Besmann, Phase equilibria and thermodynamics of the Pu-O system: 1400 K to 1610 K, Journal of Nuclear Materials 144, 141-150 (1987).
cited as the source of values for this phase
doi:10.1016/0022-3115(64)90132-1 T.D. Chikalla, C.E. McNeilly, R.E. Skavdahl, The plutonium-oxygen system, Journal of Nuclear Materials 12, 131-141 (1964).
cited as the source of values for this phase

PUO2_C1 (O–Pu)

Id: phase:o-pu:puo2-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 3 of 3 calculated diagram(s): 300–3043.58 K, x(O) 0.62007–0.66667
Literature: 38 values (38 accepted) from 1 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:o-pu:puo2-c1
paper: paper:10.1016/j.jnucmat.2008.06.013:PuO2, paper:10.1016/j.jnucmat.2008.06.013:PuO2(2), paper:10.1016/j.jnucmat.2008.06.013:PuO2-x
tdb: tdb:PuO-08Gue.tdb:PUO2_C1, tdb:PuO-11Gue.tdb:PUO2_C1, tdb:PuO-23Fou.tdb:PUO2_C1

TDB models of PUO2_C1 (3): PHASE and CONSTITUENT statements as written

PuO-08Gue.tdb: PUO2_C1, type code %, sha256 8750a98340781a5d…

89: PHASE PUO2_C1:I % 2 1 2 !
90: CONST PUO2_C1:I : PU+3 PU+4 : O-2 VA : !

PuO-11Gue.tdb: PUO2_C1, type code %, sha256 15a7df38baf15590…

95: PHASE PUO2_C1:I % 3 1 2 1 !
96: CONST PUO2_C1:I : PU+3 PU+4 : O-2% VA : O-2 VA% : !

PuO-23Fou.tdb: PUO2_C1, type code %, sha256 fa82e84a7efa7216…

101: PHASE PUO2_C1:I % 3 1 2 1 !
102: CONST PUO2_C1:I : PU+3 PU+4 : O-2% VA : O-2 VA% : !

Example references (10 of 11; assessments first):

doi:10.1016/j.jnucmat.2008.06.013 Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2022.102523 P. Fouquet-Métivier, P.M. Martin, D. Manara, K. Dardenne, J. Rothe, P.C.M. Fossati et al., Investigation of the solid/liquid phase transitions in the U–Pu–O system, Calphad 80, 102523 (2023).
assessment that models this phase
doi: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:10.1007/bf02841705 H. A. Wriedt, The O-Pu (Oxygen-Plutonium) system, Bulletin of Alloy Phase Diagrams 11, 184-202 (1990).
cited as the source of values for this phase
doi:10.1016/0022-3115(64)90132-1 T.D. Chikalla, C.E. McNeilly, R.E. Skavdahl, The plutonium-oxygen system, Journal of Nuclear Materials 12, 131-141 (1964).
cited as the source of values for this phase
doi:10.1016/0022-3115(76)90114-8 Jean-Claude Boivineau, Etude par rayons x du diagramme plutonium-oxygene de la temperature ambiante jusqu'a 1100°c, Journal of Nuclear Materials 60, 31-38 (1976).
cited as the source of values for this phase
doi:10.1016/0022-3115(87)90289-3 T.M. Besmann, Phase equilibria and thermodynamics of the Pu-O system: 1400 K to 1610 K, Journal of Nuclear Materials 144, 141-150 (1987).
cited as the source of values for this phase
doi:10.1063/1.441691 Howard E. Flotow, Marvin Tetenbaum, Heat capacity and thermodynamic functions of β-242Pu2O3 from 8 to 350 K. Contributions to the excess entropy, The Journal of Chemical Physics 74, 5269-5277 (1981).
cited as the source of values for this phase
doi: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)90039-1 Gerald K. Johnson, Erven H. Van Deventer, Owen L. Kruger, Ward N. Hubbard, The enthalpies of formation of plutonium dioxide and plutonium mononitride, The Journal of Chemical Thermodynamics 1, 89-98 (1969).
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). doi: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). doi: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.

@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}
}