H–V phases

10 phases (tier A 4, liquid 1, gas 2, needs_review 3); 5 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 · H–V system page · Markdown · field reference

Phases of the H–V system (10)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:h-v:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2188.28 K, x(H) 0–0.42255	0	1
FCC_A1 phase:h-v:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
GAS phase:h-v:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300.25–4000 K, x(H) 0–1	0	1
H2GAS phase:h-v:h2gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–1092.75 K, x(H) 1–1	0	1
HCP_A3 phase:h-v: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:h-v:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 2183–3757.23 K, x(H) 0–0.00508	0	1
V3H2 phase:h-v:v3h2		needs_review	not stable in 1 calculated diagram(s)	0	1
VH_BETA_2 phase:h-v:vh-2-beta		needs_review	not stable in 1 calculated diagram(s)	0	1
VH_BETA_ORD phase:h-v:vh-beta-ord		needs_review	stable in 1 of 1 calculated diagram(s): 300–467.32 K, x(H) 0.29435–0.48121	0	1
VH2_C1 phase:h-v:vh2-c1	CaF2 · C1 · cF12 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	2	1

BCC_A2 (H–V)

Id: phase:h-v: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): 300–2188.28 K, x(H) 0–0.42255
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:h-v:bcc-a2
tdb: tdb:VH-08Uki.tdb:BCC_A2

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

VH-08Uki.tdb: BCC_A2, type code %B, sha256 0027aaa295da99fa…

40: PHASE BCC_A2 %B 2 1 6 !
41: CONST BCC_A2 : V : H VA% : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

FCC_A1 (H–V)

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

Names (2): corpus: corpus:phase:h-v:fcc-a1
tdb: tdb:VH-08Uki.tdb:FCC_A1

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

VH-08Uki.tdb: FCC_A1, type code %A, sha256 0027aaa295da99fa…

35: PHASE FCC_A1 %A 2 1 1 !
36: CONST FCC_A1 : V : H VA% : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

GAS (H–V)

Id: phase:h-v:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300.25–4000 K, x(H) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:h-v:gas
tdb: tdb:VH-08Uki.tdb:GAS

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

VH-08Uki.tdb: GAS, type code %, sha256 0027aaa295da99fa…

69: PHASE GAS:G % 1 1 !
70: CONST GAS:G : H H2 V : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

H2GAS (H–V)

Id: phase:h-v:h2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1092.75 K, x(H) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:h-v:h2gas
tdb: tdb:VH-08Uki.tdb:H2GAS

TDB models of H2GAS (1): PHASE and CONSTITUENT statements as written

VH-08Uki.tdb: H2GAS, type code %, sha256 0027aaa295da99fa…

72: PHASE H2GAS % 1 1 !
73: CONST H2GAS : H2 : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

HCP_A3 (H–V)

Id: phase:h-v: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:h-v:hcp-a3
tdb: tdb:VH-08Uki.tdb:HCP_A3

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

VH-08Uki.tdb: HCP_A3, type code %A, sha256 0027aaa295da99fa…

45: PHASE HCP_A3 %A 2 1 0.5 !
46: CONST HCP_A3 : V : H VA% : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

LIQUID (H–V)

Id: phase:h-v:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 2183–3757.23 K, x(H) 0–0.00508
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:h-v:liquid
tdb: tdb:VH-08Uki.tdb:LIQUID

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

VH-08Uki.tdb: LIQUID, type code %, sha256 0027aaa295da99fa…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : H V : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

V3H2 (H–V)

Id: phase:h-v:v3h2; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (sgte_mmc2): (V3H2) — Hallstedt 2025 mmc2 row for V3H2: V3H2
Stoichiometry: H 0.4000, V 0.6000
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:h-v:v3h2
tdb: tdb:VH-08Uki.tdb:V3H2

TDB models of V3H2 (1): PHASE and CONSTITUENT statements as written

VH-08Uki.tdb: V3H2, type code %, sha256 0027aaa295da99fa…

61: PHASE V3H2 % 2 3 2 !
62: CONST V3H2 : V : H : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

VH_BETA_2 (H–V)

Id: phase:h-v:vh-2-beta; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:2; no_structure_token
Candidate (sgte_mmc2): V2H · tI56 · I4_1/amd (141) — Hallstedt 2025 mmc2 row for VH_BETA_2: VH-beta-2 (disordered)
Candidate (tdb_comment): V2H · tI56 · I4_1/amd — VH-08Uki.tdb: 'Prototype V2H (tI56, I4_1/amd), beta-2'
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:h-v:vh-2-beta
tdb: tdb:VH-08Uki.tdb:VH_BETA_2

TDB models of VH_BETA_2 (1): PHASE and CONSTITUENT statements as written

VH-08Uki.tdb: VH_BETA_2, type code %, sha256 0027aaa295da99fa…

51: PHASE VH_BETA_2 % 2 1 1 !
52: CONST VH_BETA_2 : H% VA : V : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

VH_BETA_ORD (H–V)

Id: phase:h-v:vh-beta-ord; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:ORD; no_structure_token
Candidate (sgte_mmc2): V2H · mC6 · C2/m (12) — Hallstedt 2025 mmc2 row for VH_BETA_ORD: VH-beta-1 (ordered)
Candidate (tdb_comment): V2H · mC6 · C2/m — VH-08Uki.tdb: 'Prototype V2H (mC6, C2/m), beta-1'
Stability: stable in 1 of 1 calculated diagram(s): 300–467.32 K, x(H) 0.29435–0.48121
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:h-v:vh-beta-ord
tdb: tdb:VH-08Uki.tdb:VH_BETA_ORD

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

VH-08Uki.tdb: VH_BETA_ORD, type code %O, sha256 0027aaa295da99fa…

56: PHASE VH_BETA_ORD %O 3 0.5 0.5 1 !
57: CONST VH_BETA_ORD : H% VA : H VA% : V : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
assessment that models this phase

VH2_C1 (H–V)

Id: phase:h-v:vh2-c1; status assigned
Structure: CaF2 · C1 · cF12 · Fm-3m (225); type st:c1-caf2-cf12; tier A: standard phase name; confidence high
Stability: not stable in 1 calculated diagram(s)
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-v:vh2-c1
paper: paper:10.2320/matertrans.mb200810:δ-VH2
tdb: tdb:VH-08Uki.tdb:VH2_C1

TDB models of VH2_C1 (1): PHASE and CONSTITUENT statements as written

VH-08Uki.tdb: VH2_C1, type code %, sha256 0027aaa295da99fa…

66: PHASE VH2_C1 % 2 1 2 !
67: CONST VH2_C1 : V : H% VA : !

Example references (1 of 1; assessments first):

doi:10.2320/matertrans.MB200810 S. Ukita, H. Ohtani, M. Hasebe, Mater. Trans. (JIM), 49, 2528-33(2008).
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}
}