Ca–I phases

8 phases (tier A 4, liquid 2, gas 1, needs_review 1); 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 · Ca–I system page · Markdown · field reference

Phases of the Ca–I system (8)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:ca-i:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
CAI2_C6 phase:ca-i:cai2-c6	CdI2 · C6 · hP3 · P-3m1 (164)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–665 K, x(I) 0.66667–0.66667	1
FCC_A1 phase:ca-i:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–665 K, x(I) 0–0	1
GAS phase:ca-i:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 1788.09–1795.49 K, x(I) 0–0.2952	1
HCP_A3 phase:ca-i:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
ORTHORHOMBIC_I phase:ca-i:i-orthorhombic		needs_review	stable in 1 of 1 calculated diagram(s): 300–386.7 K, x(I) 1–1	1
ION phase:ca-i:ion	liquid	liquid	stable in 1 of 1 calculated diagram(s): 386.06–1795.49 K, x(I) 0–1	1
LIQUID phase:ca-i:liquid	liquid	liquid	not stable in 1 calculated diagram(s)	1

BCC_A2 (Ca–I)

Id: phase:ca-i:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: Ca 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:ca-i:bcc-a2
tdb: tdb:CaI-92Sta.tdb:BCC_A2

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

CaI-92Sta.tdb: BCC_A2, type code %B, sha256 f96626f929260b85…

50: PHASE BCC_A2 %B 2 1 3 !
51: CONST BCC_A2 : CA : VA : !

CAI2_C6 (Ca–I)

Id: phase:ca-i:cai2-c6; status assigned
Structure: CdI2 · C6 · hP3 · P-3m1 (164); type st:c6-cdi2-hp3; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–665 K, x(I) 0.66667–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-i:cai2-c6
tdb: tdb:CaI-92Sta.tdb:CAI2_C6

TDB models of CAI2_C6 (1): PHASE and CONSTITUENT statements as written

CaI-92Sta.tdb: CAI2_C6, type code %, sha256 f96626f929260b85…

65: PHASE CAI2_C6:I % 2 1 2 !
66: CONST CAI2_C6:I : CA+2 : I-1 : !

FCC_A1 (Ca–I)

Id: phase:ca-i:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Ca 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–665 K, x(I) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-i:fcc-a1
tdb: tdb:CaI-92Sta.tdb:FCC_A1

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

CaI-92Sta.tdb: FCC_A1, type code %A, sha256 f96626f929260b85…

45: PHASE FCC_A1 %A 2 1 1 !
46: CONST FCC_A1 : CA : VA : !

GAS (Ca–I)

Id: phase:ca-i:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1788.09–1795.49 K, x(I) 0–0.2952
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-i:gas
tdb: tdb:CaI-92Sta.tdb:GAS

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

CaI-92Sta.tdb: GAS, type code %, sha256 f96626f929260b85…

68: PHASE GAS:G % 1 1 !
69: CONST GAS:G : CA CA2 CAI CAI2 I I2 : !

HCP_A3 (Ca–I)

Id: phase:ca-i: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: Ca 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:ca-i:hcp-a3
tdb: tdb:CaI-92Sta.tdb:HCP_A3

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

CaI-92Sta.tdb: HCP_A3, type code %A, sha256 f96626f929260b85…

55: PHASE HCP_A3 %A 2 1 0.5 !
56: CONST HCP_A3 : CA : VA : !

ORTHORHOMBIC_I (Ca–I)

Id: phase:ca-i:i-orthorhombic; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:ORTHORHOMBIC; no_structure_token
Candidate (sgte_mmc2): I2 · A14 · oC8 · Cmce (64) — Hallstedt 2025 mmc2 row for ORTHORHOMBIC_I: I2
Candidate (tdb_comment): I2 · oC8 · Cmce, A14 — CaI-92Sta.tdb: 'Prototype I2 (oC8, Cmce, A14)'
Stability: stable in 1 of 1 calculated diagram(s): 300–386.7 K, x(I) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-i:i-orthorhombic
tdb: tdb:CaI-92Sta.tdb:ORTHORHOMBIC_I

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

CaI-92Sta.tdb: ORTHORHOMBIC_I, type code %, sha256 f96626f929260b85…

60: PHASE ORTHORHOMBIC_I % 1 1 !
61: CONST ORTHORHOMBIC_I : I2 : !

ION (Ca–I)

Id: phase:ca-i:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 386.06–1795.49 K, x(I) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-i:ion
tdb: tdb:CaI-92Sta.tdb:ION

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

CaI-92Sta.tdb: ION, type code %, sha256 f96626f929260b85…

37: PHASE ION:Y % 2 1 1 !
38: CONST ION:Y : CA+2 : I-1 VA I2 : !

LIQUID (Ca–I)

Id: phase:ca-i:liquid; status assigned
Structure: liquid; type st:liquid; liquid; 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:ca-i:liquid
tdb: tdb:CaI-92Sta.tdb:LIQUID

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

CaI-92Sta.tdb: LIQUID, type code %, sha256 f96626f929260b85…

40: PHASE LIQUID:L % 1 1 !
41: CONST LIQUID:L : CA I2 : !

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}
}