Th–U phases

8 phases (tier A 6, liquid 1, needs_review 1); 7 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 · Th–U system page · Markdown · field reference

Phases of the Th–U system (8)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
ORTHORHOMBIC_A20 phase:th-u:a20-orthorhombic	alpha-U · A20 · oC4 · Cmcm (63)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–944.37 K, x(U) 0.99779–1	0	2
BCC_A2 phase:th-u:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1050–2030.99 K, x(U) 0–1	6	1
FCC_A1 phase:th-u:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1636.19 K, x(U) 0–0.69	4	2
HCP_A3 phase:th-u:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
LIQUID phase:th-u:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 1380–4000 K, x(U) 0–1	6	2
BCC_TH phase:th-u:th-bcc	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1380–2022.99 K, x(U) 0–0.09137	0	1
BCC_U phase:th-u:u-bcc	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1048.19–1842.99 K, x(U) 0.26–1	0	1
TETRAGONAL_U phase:th-u:u-tetragonal		needs_review	stable in 2 of 2 calculated diagram(s): 942.02–1403.19 K, x(U) 0.99741–1	0	2

ORTHORHOMBIC_A20 (Th–U)

Id: phase:th-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
Stability: stable in 2 of 2 calculated diagram(s): 300–944.37 K, x(U) 0.99779–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:th-u:a20-orthorhombic
tdb: tdb:ThU-09Li.tdb:ORTHORHOMBIC_A20, tdb:ThU-14Ben.tdb:ORTHORHOMBIC_A20

TDB models of ORTHORHOMBIC_A20 (2): PHASE and CONSTITUENT statements as written

ThU-09Li.tdb: ORTHORHOMBIC_A20, type code %, sha256 64caf9670047ca6e…

42: PHASE ORTHORHOMBIC_A20 % 1 1 !
43: CONST ORTHORHOMBIC_A20 : TH U% : !

ThU-14Ben.tdb: ORTHORHOMBIC_A20, type code %, sha256 66891b9d678576aa…

49: PHASE ORTHORHOMBIC_A20 % 1 1 !
50: CONST ORTHORHOMBIC_A20 : U : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase
doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models this phase

BCC_A2 (Th–U)

Id: phase:th-u:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1050–2030.99 K, x(U) 0–1
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:th-u:bcc-a2
paper: paper:10.1016/j.jallcom.2008.09.051:βTh, paper:10.1016/j.jallcom.2008.09.051:γU
tdb: tdb:ThU-09Li.tdb:BCC_A2

TDB models of BCC_A2 (1): PHASE and CONSTITUENT statements as written

ThU-09Li.tdb: BCC_A2, type code %B, sha256 64caf9670047ca6e…

32: PHASE BCC_A2 %B 2 1 3 !
33: CONST BCC_A2 : TH% U% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase; reports values for this phase

FCC_A1 (Th–U)

Id: phase:th-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: stable in 2 of 2 calculated diagram(s): 300–1636.19 K, x(U) 0–0.69
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:th-u:fcc-a1
paper: paper:10.1016/j.jallcom.2008.09.051:αTh
tdb: tdb:ThU-09Li.tdb:FCC_A1, tdb:ThU-14Ben.tdb:FCC_A1

TDB models of FCC_A1 (2): PHASE and CONSTITUENT statements as written

ThU-09Li.tdb: FCC_A1, type code %A, sha256 64caf9670047ca6e…

27: PHASE FCC_A1 %A 2 1 1 !
28: CONST FCC_A1 : TH% U : VA : !

ThU-14Ben.tdb: FCC_A1, type code %A, sha256 66891b9d678576aa…

29: PHASE FCC_A1 %A 2 1 1 !
30: CONST FCC_A1 : TH% U : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase; reports values for this phase
doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models this phase

HCP_A3 (Th–U)

Id: phase:th-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
Stability: not stable in 1 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:th-u:hcp-a3
tdb: tdb:ThU-09Li.tdb:HCP_A3

TDB models of HCP_A3 (1): PHASE and CONSTITUENT statements as written

ThU-09Li.tdb: HCP_A3, type code %A, sha256 64caf9670047ca6e…

37: PHASE HCP_A3 %A 2 1 0.5 !
38: CONST HCP_A3 : TH U : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase

LIQUID (Th–U)

Id: phase:th-u:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1380–4000 K, x(U) 0–1
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:th-u:liquid
paper: paper:10.1016/j.jallcom.2008.09.051:L2
tdb: tdb:ThU-09Li.tdb:LIQUID, tdb:ThU-14Ben.tdb:LIQUID

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

ThU-09Li.tdb: LIQUID, type code %, sha256 64caf9670047ca6e…

22: PHASE LIQUID:L % 1 1 !
23: CONST LIQUID:L : TH U : !

ThU-14Ben.tdb: LIQUID, type code %, sha256 66891b9d678576aa…

24: PHASE LIQUID:L % 1 1 !
25: CONST LIQUID:L : TH U : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase; reports values for this phase
doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models this phase

BCC_TH (Th–U)

Id: phase:th-u:th-bcc; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1380–2022.99 K, x(U) 0–0.09137
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:th-u:th-bcc
tdb: tdb:ThU-14Ben.tdb:BCC_TH

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

ThU-14Ben.tdb: BCC_TH, type code %B, sha256 66891b9d678576aa…

44: PHASE BCC_TH %B 2 1 3 !
45: CONST BCC_TH : TH% U : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models this phase

BCC_U (Th–U)

Id: phase:th-u:u-bcc; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1048.19–1842.99 K, x(U) 0.26–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:th-u:u-bcc
tdb: tdb:ThU-14Ben.tdb:BCC_U

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

ThU-14Ben.tdb: BCC_U, type code %B, sha256 66891b9d678576aa…

39: PHASE BCC_U %B 2 1 3 !
40: CONST BCC_U : TH U% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models this phase

TETRAGONAL_U (Th–U)

Id: phase:th-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 — ThU-09Li.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — ThU-14Ben.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
Stability: stable in 2 of 2 calculated diagram(s): 942.02–1403.19 K, x(U) 0.99741–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:th-u:u-tetragonal
tdb: tdb:ThU-09Li.tdb:TETRAGONAL_U, tdb:ThU-14Ben.tdb:TETRAGONAL_U

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

ThU-09Li.tdb: TETRAGONAL_U, type code %, sha256 64caf9670047ca6e…

47: PHASE TETRAGONAL_U % 1 1 !
48: CONST TETRAGONAL_U : TH U% : !

ThU-14Ben.tdb: TETRAGONAL_U, type code %, sha256 66891b9d678576aa…

54: PHASE TETRAGONAL_U % 1 1 !
55: CONST TETRAGONAL_U : U : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jallcom.2008.09.051 Z.S. Li, X.J. Liu, C.P. Wang, Thermodynamic modeling of the Th–U, Th–Zr and Th–U–Zr systems, Journal of Alloys and Compounds 476, 193-198 (2009).
assessment that models this phase
doi:10.1016/j.jnucmat.2014.02.001 O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014).
assessment that models 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}
}