B–U phases

10 phases (tier A 7, liquid 1, needs_review 2); 8 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 · B–U system page · Markdown · field reference

Phases of the B–U system (10)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
ORTHORHOMBIC_A20 phase:b-u:a20-orthorhombic	alpha-U · A20 · oC4 · Cmcm (63)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–942.02 K, x(B) 0–0	0	1
BETA_RHOMBO_B phase:b-u:b-beta-rhombo		needs_review	stable in 1 of 1 calculated diagram(s): 300–2351.71 K, x(B) 1–1	0	1
BCC_A2 phase:b-u:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1048.99–3272.99 K, x(B) 0–0	0	1
FCC_A1 phase:b-u:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
HCP_A3 phase:b-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:b-u:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1381.19–4000 K, x(B) 0–1	18	1
TETRAGONAL_U phase:b-u:u-tetragonal		needs_review	stable in 1 of 1 calculated diagram(s): 942.02–1048.99 K, x(B) 0–0	0	1
UB12_D2F phase:b-u:ub12-d2f	UB12 · D2_f · cF52 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2457.96 K, x(B) 0.92308–0.92308	7	1
UB2_C32 phase:b-u:ub2-c32	AlB2 · C32 · hP3 · P6/mmm (191)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2670.95 K, x(B) 0.66667–0.66667	8	1
UB4_D1E phase:b-u:ub4-d1e	UB4 · D1_e · tP20 · P4/mbm (127)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2722.24 K, x(B) 0.8–0.8	3	1

ORTHORHOMBIC_A20 (B–U)

Id: phase:b-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 1 of 1 calculated diagram(s): 300–942.02 K, x(B) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-u:a20-orthorhombic
tdb: tdb:UB-01Che.tdb:ORTHORHOMBIC_A20

TDB models of ORTHORHOMBIC_A20 (1): PHASE and CONSTITUENT statements as written

UB-01Che.tdb: ORTHORHOMBIC_A20, type code %, sha256 6807da8a6672bb65…

43: PHASE ORTHORHOMBIC_A20 % 1 1 !
44: CONST ORTHORHOMBIC_A20 : U : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

BETA_RHOMBO_B (B–U)

Id: phase:b-u:b-beta-rhombo; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:RHOMBO; no_structure_token
Candidate (sgte_mmc2): beta-B · hR105 · R-3m (166) — Hallstedt 2025 mmc2 row for BETA_RHOMBO_B: beta-B
Candidate (tdb_comment): beta-B · hR105 · R-3m — UB-01Che.tdb: 'Prototype beta-B (hR105, R-3m)'
Stoichiometry: B 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–2351.71 K, x(B) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-u:b-beta-rhombo
tdb: tdb:UB-01Che.tdb:BETA_RHOMBO_B

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

UB-01Che.tdb: BETA_RHOMBO_B, type code %, sha256 6807da8a6672bb65…

53: PHASE BETA_RHOMBO_B % 1 1 !
54: CONST BETA_RHOMBO_B : B : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

BCC_A2 (B–U)

Id: phase:b-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 1 of 1 calculated diagram(s): 1048.99–3272.99 K, x(B) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-u:bcc-a2
tdb: tdb:UB-01Che.tdb:BCC_A2

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

UB-01Che.tdb: BCC_A2, type code %B, sha256 6807da8a6672bb65…

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

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

FCC_A1 (B–U)

Id: phase:b-u:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: U 1.0000
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:b-u:fcc-a1
tdb: tdb:UB-01Che.tdb:FCC_A1

TDB models of FCC_A1 (1): PHASE and CONSTITUENT statements as written

UB-01Che.tdb: FCC_A1, type code %A, sha256 6807da8a6672bb65…

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

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

HCP_A3 (B–U)

Id: phase:b-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 1 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-u:hcp-a3
tdb: tdb:UB-01Che.tdb:HCP_A3

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

UB-01Che.tdb: HCP_A3, type code %A, sha256 6807da8a6672bb65…

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

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

LIQUID (B–U)

Id: phase:b-u:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1381.19–4000 K, x(B) 0–1
Literature: 18 values (18 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:b-u:liquid
paper: paper:10.1016/s0022-3115(00)00713-3:L
tdb: tdb:UB-01Che.tdb:LIQUID

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

UB-01Che.tdb: LIQUID, type code %, sha256 6807da8a6672bb65…

23: PHASE LIQUID:L % 1 1 !
24: CONST LIQUID:L : B U : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase; reports values for this phase

TETRAGONAL_U (B–U)

Id: phase:b-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 — UB-01Che.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
Stoichiometry: U 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 942.02–1048.99 K, x(B) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-u:u-tetragonal
tdb: tdb:UB-01Che.tdb:TETRAGONAL_U

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

UB-01Che.tdb: TETRAGONAL_U, type code %, sha256 6807da8a6672bb65…

48: PHASE TETRAGONAL_U % 1 1 !
49: CONST TETRAGONAL_U : U : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase

UB12_D2F (B–U)

Id: phase:b-u:ub12-d2f; status assigned
Structure: UB12 · D2_f · cF52 · Fm-3m (225); type st:d2-f-ub12-cf52; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaabhal and oqmd-4445, space group 225
Stoichiometry: B 0.9231, U 0.0769
Stability: stable in 1 of 1 calculated diagram(s): 300–2457.96 K, x(B) 0.92308–0.92308
Literature: 7 values (7 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:b-u:ub12-d2f
mp: mp:mp-aaaabhal
oqmd: oqmd:oqmd-4445
paper: paper:10.1016/s0022-3115(00)00713-3:UB12
tdb: tdb:UB-01Che.tdb:UB12_D2F

TDB models of UB12_D2F (1): PHASE and CONSTITUENT statements as written

UB-01Che.tdb: UB12_D2F, type code %, sha256 6807da8a6672bb65…

68: PHASE UB12_D2F % 2 1 12 !
69: CONST UB12_D2F : U : B : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase; reports values for this phase

UB2_C32 (B–U)

Id: phase:b-u:ub2-c32; status assigned
Structure: AlB2 · C32 · hP3 · P6/mmm (191); type st:c32-alb2-hp3; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaacgg and oqmd-646133, space group 191
Stoichiometry: B 0.6667, U 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–2670.95 K, x(B) 0.66667–0.66667
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:b-u:ub2-c32
mp: mp:mp-aaaaacgg
oqmd: oqmd:oqmd-646133
paper: paper:10.1016/s0022-3115(00)00713-3:UB2
tdb: tdb:UB-01Che.tdb:UB2_C32

TDB models of UB2_C32 (1): PHASE and CONSTITUENT statements as written

UB-01Che.tdb: UB2_C32, type code %, sha256 6807da8a6672bb65…

58: PHASE UB2_C32 % 2 1 2 !
59: CONST UB2_C32 : U : B : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase; reports values for this phase

UB4_D1E (B–U)

Id: phase:b-u:ub4-d1e; status assigned
Structure: UB4 · D1_e · tP20 · P4/mbm (127); type st:d1-e-ub4-tp20; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaaaxv and oqmd-4686, space group 127
Stoichiometry: B 0.8000, U 0.2000
Stability: stable in 1 of 1 calculated diagram(s): 300–2722.24 K, x(B) 0.8–0.8
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:b-u:ub4-d1e
mp: mp:mp-aaaaaaxv
oqmd: oqmd:oqmd-4686
paper: paper:10.1016/s0022-3115(00)00713-3:UB4
tdb: tdb:UB-01Che.tdb:UB4_D1E

TDB models of UB4_D1E (1): PHASE and CONSTITUENT statements as written

UB-01Che.tdb: UB4_D1E, type code %, sha256 6807da8a6672bb65…

63: PHASE UB4_D1E % 2 1 4 !
64: CONST UB4_D1E : U : B : !

Example references (1 of 1; assessments first):

doi:10.1016/S0022-3115(00)00713-3 P.-Y. Chevalier, E. Fischer, J. Nucl. Mater., 288, 100-29(2001).
assessment that models this phase; reports 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}
}