Ca–H phases

7 phases (tier A 4, liquid 1, gas 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 · Ca–H system page · Markdown · field reference

Phases of the Ca–H system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:ca-h:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 688.01–1306.02 K, x(H) 0–0.3427	0	2
CAH2_BETA phase:ca-h:cah2-beta		needs_review	stable in 2 of 2 calculated diagram(s): 1053.15–1257.01 K, x(H) 0.66667–0.66667	2	2
CAH2_C37 phase:ca-h:cah2-c37	Co2Si · C37 · oP12 · Pnma (62)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1053.28 K, x(H) 0.66667–0.66667	9	2
FCC_A1 phase:ca-h:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1306.02 K, x(H) 0–0.01797	0	2
GAS phase:ca-h:gas	gas	gas	stable in 2 of 2 calculated diagram(s): 300–2500 K, x(H) 0–1	0	2
HCP_A3 phase:ca-h:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 624.48–878.76 K, x(H) 0.01318–0.16929	1	2
LIQUID phase:ca-h:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 1110–2111.52 K, x(H) 0–0.48736	0	2

BCC_A2 (Ca–H)

Id: phase:ca-h: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 2 of 2 calculated diagram(s): 688.01–1306.02 K, x(H) 0–0.3427
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-h:bcc-a2
tdb: tdb:CaH-11Wan.tdb:BCC_A2, tdb:CaH-12Wan.tdb:BCC_A2

TDB models of BCC_A2 (2): PHASE and CONSTITUENT statements as written

CaH-11Wan.tdb: BCC_A2, type code %B, sha256 10f2af8543f879ee…

40: PHASE BCC_A2 %B 2 1 1.5 !
41: CONST BCC_A2 : CA : H VA% : !

CaH-12Wan.tdb: BCC_A2, type code %B, sha256 e8d5c286231e6b11…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : CA : H VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase
doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase

CAH2_BETA (Ca–H)

Id: phase:ca-h:cah2-beta; status needs_review
No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
Candidate (dft_mp): Pnma (62) — on-hull MP CaH2 at x(H)=0.6667
Candidate (dft_oqmd): Pnma (62) — on-hull OQMD Ca1 H2 at x(H)=0.6667
Candidate (sgte_mmc2): (CaH2-beta) · Fm-3m (225) — Hallstedt 2025 mmc2 row for CAH2_BETA: CaH2-beta (possibly CaF2 structure)
Stoichiometry: Ca 0.3333, H 0.6667
Stability: stable in 2 of 2 calculated diagram(s): 1053.15–1257.01 K, x(H) 0.66667–0.66667
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-h:cah2-beta
paper: paper:10.1016/j.ijhydene.2011.08.018:βCaH2
tdb: tdb:CaH-11Wan.tdb:CAH2_BETA, tdb:CaH-12Wan.tdb:CAH2_BETA

TDB models of CAH2_BETA (2): PHASE and CONSTITUENT statements as written

CaH-11Wan.tdb: CAH2_BETA, type code %, sha256 10f2af8543f879ee…

55: PHASE CAH2_BETA % 2 1 2 !
56: CONST CAH2_BETA : CA : H : !

CaH-12Wan.tdb: CAH2_BETA, type code %, sha256 e8d5c286231e6b11…

52: PHASE CAH2_BETA % 2 1 2 !
53: CONST CAH2_BETA : CA : H : !

Example references (2 of 2; assessments first):

doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase

CAH2_C37 (Ca–H)

Id: phase:ca-h:cah2-c37; status assigned
Structure: Co2Si · C37 · oP12 · Pnma (62); type st:c37-co2si-op12; tier A: standard phase name; confidence high
Stoichiometry: Ca 0.3333, H 0.6667
Stability: stable in 2 of 2 calculated diagram(s): 300–1053.28 K, x(H) 0.66667–0.66667
Literature: 9 values (9 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-h:cah2-c37
paper: paper:10.1016/j.ijhydene.2011.08.018:αCaH2
tdb: tdb:CaH-11Wan.tdb:CAH2_C37, tdb:CaH-12Wan.tdb:CAH2_C37

TDB models of CAH2_C37 (2): PHASE and CONSTITUENT statements as written

CaH-11Wan.tdb: CAH2_C37, type code %, sha256 10f2af8543f879ee…

50: PHASE CAH2_C37 % 2 1 2 !
51: CONST CAH2_C37 : CA : H : !

CaH-12Wan.tdb: CAH2_C37, type code %, sha256 e8d5c286231e6b11…

47: PHASE CAH2_C37 % 2 1 2 !
48: CONST CAH2_C37 : CA : H : !

Example references (2 of 2; assessments first):

doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase

FCC_A1 (Ca–H)

Id: phase:ca-h: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): 300–1306.02 K, x(H) 0–0.01797
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-h:fcc-a1
tdb: tdb:CaH-11Wan.tdb:FCC_A1, tdb:CaH-12Wan.tdb:FCC_A1

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

CaH-11Wan.tdb: FCC_A1, type code %A, sha256 10f2af8543f879ee…

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

CaH-12Wan.tdb: FCC_A1, type code %A, sha256 e8d5c286231e6b11…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : CA% : H VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase
doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase

GAS (Ca–H)

Id: phase:ca-h:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–2500 K, x(H) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-h:gas
tdb: tdb:CaH-11Wan.tdb:GAS, tdb:CaH-12Wan.tdb:GAS

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

CaH-11Wan.tdb: GAS, type code %, sha256 10f2af8543f879ee…

58: PHASE GAS:G % 1 1 !
59: CONST GAS:G : CA CA2 CAH H H2 : !

CaH-12Wan.tdb: GAS, type code %, sha256 e8d5c286231e6b11…

55: PHASE GAS:G % 1 1 !
56: CONST GAS:G : CA CA2 CAH H H2 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase
doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase

HCP_A3 (Ca–H)

Id: phase:ca-h: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: stable in 2 of 2 calculated diagram(s): 624.48–878.76 K, x(H) 0.01318–0.16929
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-h:hcp-a3
paper: paper:10.1016/j.ijhydene.2011.08.018:CaH
tdb: tdb:CaH-11Wan.tdb:HCP_A3, tdb:CaH-12Wan.tdb:HCP_A3

TDB models of HCP_A3 (2): PHASE and CONSTITUENT statements as written

CaH-11Wan.tdb: HCP_A3, type code %A, sha256 10f2af8543f879ee…

45: PHASE HCP_A3 %A 1 1 !
46: CONST HCP_A3 : CA CAH2 : !

CaH-12Wan.tdb: HCP_A3, type code %A, sha256 e8d5c286231e6b11…

42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : CA : H VA% : !

Example references (2 of 2; assessments first):

doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase

LIQUID (Ca–H)

Id: phase:ca-h:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1110–2111.52 K, x(H) 0–0.48736
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-h:liquid
tdb: tdb:CaH-11Wan.tdb:LIQUID, tdb:CaH-12Wan.tdb:LIQUID

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

CaH-11Wan.tdb: LIQUID, type code %, sha256 10f2af8543f879ee…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : CA CAH2 H : !

CaH-12Wan.tdb: LIQUID, type code %, sha256 e8d5c286231e6b11…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : CA H : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-012-9997-z Man Wang, Weihua Sun, Chunsheng Sha, Biao Hu, Yong Du, Lixian Sun et al., Thermodynamic Modeling of the Li-H and Ca-H Systems, J. Phase Equilib. Diffus. 33, 89-96 (2012).
assessment that models this phase
doi:10.1016/j.ijhydene.2011.08.018 Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011).
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}
}