Ca–S phases

8 phases (tier A 4, liquid 2, needs_review 2); 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–S system page · Markdown · field reference

Phases of the Ca–S system (8)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:ca-s:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1112–1115 K, x(S) 0–0	1
CAS_B1 phase:ca-s:cas-b1	NaCl · B1 · cF8 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–505 K, x(S) 0.5–0.5	1
FCC_A1 phase:ca-s:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–505 K, x(S) 0–0	1
HCP_A3 phase:ca-s:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
ION phase:ca-s:ion	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1112–1115 K, x(S) 0–0.00249	1
LIQUID phase:ca-s:liquid	liquid	liquid	not stable in 1 calculated diagram(s)	1
MONOCLINIC_S phase:ca-s:s-monoclinic		needs_review	not stable in 1 calculated diagram(s)	1
ORTHORHOMBIC_S phase:ca-s:s-orthorhombic		needs_review	stable in 1 of 1 calculated diagram(s): 300–375 K, x(S) 1–1	1

BCC_A2 (Ca–S)

Id: phase:ca-s: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): 1112–1115 K, x(S) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-s:bcc-a2
tdb: tdb:CaS-16Dil.tdb:BCC_A2

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

CaS-16Dil.tdb: BCC_A2, type code %B, sha256 5f8df58bbc3c6087…

43: PHASE BCC_A2 %B 2 1 3 !
44: CONST BCC_A2 : CA% S : VA : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

CAS_B1 (Ca–S)

Id: phase:ca-s:cas-b1; status assigned
Structure: NaCl · B1 · cF8 · Fm-3m (225); type st:b1-nacl-cf8; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–505 K, x(S) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-s:cas-b1
tdb: tdb:CaS-16Dil.tdb:CAS_B1

TDB models of CAS_B1 (1): PHASE and CONSTITUENT statements as written

CaS-16Dil.tdb: CAS_B1, type code %, sha256 5f8df58bbc3c6087…

63: PHASE CAS_B1:I % 2 1 1 !
64: CONST CAS_B1:I : CA+2 : S-2 : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

FCC_A1 (Ca–S)

Id: phase:ca-s: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 1 of 1 calculated diagram(s): 300–505 K, x(S) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-s:fcc-a1
tdb: tdb:CaS-16Dil.tdb:FCC_A1

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

CaS-16Dil.tdb: FCC_A1, type code %A, sha256 5f8df58bbc3c6087…

38: PHASE FCC_A1 %A 2 1 1 !
39: CONST FCC_A1 : CA% S : VA : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

HCP_A3 (Ca–S)

Id: phase:ca-s: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-s:hcp-a3
tdb: tdb:CaS-16Dil.tdb:HCP_A3

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

CaS-16Dil.tdb: HCP_A3, type code %A, sha256 5f8df58bbc3c6087…

48: PHASE HCP_A3 %A 2 1 0.5 !
49: CONST HCP_A3 : CA : VA : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

ION (Ca–S)

Id: phase:ca-s:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1112–1115 K, x(S) 0–0.00249
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-s:ion
tdb: tdb:CaS-16Dil.tdb:ION

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

CaS-16Dil.tdb: ION, type code %, sha256 5f8df58bbc3c6087…

30: PHASE ION:Y % 2 1 1 !
31: CONST ION:Y : CA+2 : S-2 VA S : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

LIQUID (Ca–S)

Id: phase:ca-s:liquid; status assigned
Structure: liquid; type st:liquid; liquid; 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-s:liquid
tdb: tdb:CaS-16Dil.tdb:LIQUID

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

CaS-16Dil.tdb: LIQUID, type code %, sha256 5f8df58bbc3c6087…

33: PHASE LIQUID:L % 1 1 !
34: CONST LIQUID:L : CA : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

MONOCLINIC_S (Ca–S)

Id: phase:ca-s:s-monoclinic; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:MONOCLINIC; no_structure_token
Candidate (sgte_mmc2): beta-S · mP48 · P2_1/c (14) — Hallstedt 2025 mmc2 row for MONOCLINIC_S: beta-S
Candidate (tdb_comment): beta-S · mP48 · P2_1/a — CaS-16Dil.tdb: 'Prototype beta-S (mP48, P2_1/a)'
Stoichiometry: S 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-s:s-monoclinic
tdb: tdb:CaS-16Dil.tdb:MONOCLINIC_S

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

CaS-16Dil.tdb: MONOCLINIC_S, type code %, sha256 5f8df58bbc3c6087…

58: PHASE MONOCLINIC_S % 1 1 !
59: CONST MONOCLINIC_S : S : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
assessment that models this phase

ORTHORHOMBIC_S (Ca–S)

Id: phase:ca-s:s-orthorhombic; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:ORTHORHOMBIC; no_structure_token
Candidate (sgte_mmc2): alpha-S · A16 · oF128 · Fddd (70) — Hallstedt 2025 mmc2 row for ORTHORHOMBIC_S: alpha-S
Candidate (tdb_comment): alpha-S · oF128 · Fddd — CaS-16Dil.tdb: 'Prototype alpha-S (oF128, Fddd), A16'
Stoichiometry: S 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–375 K, x(S) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ca-s:s-orthorhombic
tdb: tdb:CaS-16Dil.tdb:ORTHORHOMBIC_S

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

CaS-16Dil.tdb: ORTHORHOMBIC_S, type code %, sha256 5f8df58bbc3c6087…

53: PHASE ORTHORHOMBIC_S % 1 1 !
54: CONST ORTHORHOMBIC_S : S : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-016-0454-2 David Dilner, Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems, J. Phase Equilib. Diffus. 37, 277-292 (2016).
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}
}