Ca–Cu phases

7 phases (tier A 4, tier C 1, liquid 1, needs_review 1); 6 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–Cu system page · Markdown · field reference

Phases of the Ca–Cu system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:ca-cu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 680.6–1124.71 K, x(Cu) 0–1e-05	0	2
CA2CU phase:ca-cu:ca2cu	Ca2Cu · oP12 · Pnma (62)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 2 of 2 calculated diagram(s): 300–785.47 K, x(Cu) 0.33333–0.33333	1	2
CACU phase:ca-cu:cacu		needs_review	stable in 2 of 2 calculated diagram(s): 300–841.26 K, x(Cu) 0.5–0.5	1	2
CACU5_D2D phase:ca-cu:cacu5-d2d	CaCu5 · D2_d · hP6 · P6/mmm (191)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1223.63 K, x(Cu) 0.83333–0.83333	0	2
FCC_A1 phase:ca-cu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2499.87 K, x(Cu) 0–1	0	2
HCP_A3 phase:ca-cu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 2 calculated diagram(s)	0	2
LIQUID phase:ca-cu:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 753.69–2500 K, x(Cu) 0–1	4	2

BCC_A2 (Ca–Cu)

Id: phase:ca-cu: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): 680.6–1124.71 K, x(Cu) 0–1e-05
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-cu:bcc-a2
tdb: tdb:CaCu-96Ris-LB.tdb:BCC_A2, tdb:CaCu-97Ais.tdb:BCC_A2

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

CaCu-96Ris-LB.tdb: BCC_A2, type code %B, sha256 a46c915ad7d9c07f…

31: PHASE BCC_A2 %B 2 1 3 !
32: CONST BCC_A2 : CA% CU : VA : !

CaCu-97Ais.tdb: BCC_A2, type code %B, sha256 649c86c7eee5fdbf…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : CA% CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase

CA2CU (Ca–Cu)

Id: phase:ca-cu:ca2cu; status assigned
Structure: Ca2Cu · oP12 · Pnma (62); type st:ca2cu-op12; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (dft_space_group_62_matches_6_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Ca 0.6667, Cu 0.3333
Stability: stable in 2 of 2 calculated diagram(s): 300–785.47 K, x(Cu) 0.33333–0.33333
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-cu:ca2cu
paper: paper:10.1016/s0364-5916(96)00022-3:Ca2Cu
tdb: tdb:CaCu-96Ris-LB.tdb:CA2CU, tdb:CaCu-97Ais.tdb:CA2CU

TDB models of CA2CU (2): PHASE and CONSTITUENT statements as written

CaCu-96Ris-LB.tdb: CA2CU, type code %, sha256 a46c915ad7d9c07f…

41: PHASE CA2CU % 2 2 1 !
42: CONST CA2CU : CA : CU : !

CaCu-97Ais.tdb: CA2CU, type code %, sha256 649c86c7eee5fdbf…

45: PHASE CA2CU % 2 2 1 !
46: CONST CA2CU : CA : CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase; reports values for this phase

CACU (Ca–Cu)

Id: phase:ca-cu:cacu; status needs_review
No structure assigned. Why: dft_space_group_62_matches_0_structure_types; no_structure_token; sgte_mmc2_row_disagrees_with_dft; sgte_mmc2_rows_disagree
Candidate (dft_mp): Pnma (62) — on-hull MP CaCu at x(CU)=0.5000
Candidate (dft_oqmd): Pnma (62) — on-hull OQMD Ca1 Cu1 at x(CU)=0.5000
Candidate (sgte_mmc2): CaCu-alpha · mP20 · P2_1/m (11) — Hallstedt 2025 mmc2 row for CACU: alpha-CaCu
Candidate (sgte_mmc2): CaCu-beta · oP40 · Pnma (62) — Hallstedt 2025 mmc2 row for CACU: beta-CaCu
Candidate (tdb_comment): alpha-CaCu · mP20 · P2_1/m — CaCu-96Ris-LB.tdb: 'Prototype alpha-CaCu (mP20, P2_1/m)'
Candidate (tdb_comment): alpha-CaCu · mP20 · P2_1/m — CaCu-97Ais.tdb: 'Prototype alpha-CaCu (mP20, P2_1/m)'
Stoichiometry: Ca 0.5000, Cu 0.5000
Stability: stable in 2 of 2 calculated diagram(s): 300–841.26 K, x(Cu) 0.5–0.5
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-cu:cacu
paper: paper:10.1016/s0364-5916(96)00022-3:CaCu
tdb: tdb:CaCu-96Ris-LB.tdb:CACU, tdb:CaCu-97Ais.tdb:CACU

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

CaCu-96Ris-LB.tdb: CACU, type code %, sha256 a46c915ad7d9c07f…

47: PHASE CACU % 2 1 1 !
48: CONST CACU : CA : CU : !

CaCu-97Ais.tdb: CACU, type code %, sha256 649c86c7eee5fdbf…

51: PHASE CACU % 2 1 1 !
52: CONST CACU : CA : CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase; reports values for this phase

CACU5_D2D (Ca–Cu)

Id: phase:ca-cu:cacu5-d2d; status assigned
Structure: CaCu5 · D2_d · hP6 · P6/mmm (191); type st:d2-d-cacu5-hp6; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaacuk and oqmd-10978, space group 191
Stoichiometry: Ca 0.1667, Cu 0.8333
Stability: stable in 2 of 2 calculated diagram(s): 300–1223.63 K, x(Cu) 0.83333–0.83333
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:ca-cu:cacu5-d2d
mp: mp:mp-aaaaacuk
oqmd: oqmd:oqmd-10978
tdb: tdb:CaCu-96Ris-LB.tdb:CACU5_D2D, tdb:CaCu-97Ais.tdb:CACU5_D2D

TDB models of CACU5_D2D (2): PHASE and CONSTITUENT statements as written

CaCu-96Ris-LB.tdb: CACU5_D2D, type code %, sha256 a46c915ad7d9c07f…

52: PHASE CACU5_D2D % 2 1 5 !
53: CONST CACU5_D2D : CA : CU : !

CaCu-97Ais.tdb: CACU5_D2D, type code %, sha256 649c86c7eee5fdbf…

56: PHASE CACU5_D2D % 2 1 5 !
57: CONST CACU5_D2D : CA : CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase

FCC_A1 (Ca–Cu)

Id: phase:ca-cu: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): 300–2499.87 K, x(Cu) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-cu:fcc-a1
tdb: tdb:CaCu-96Ris-LB.tdb:FCC_A1, tdb:CaCu-97Ais.tdb:FCC_A1

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

CaCu-96Ris-LB.tdb: FCC_A1, type code %A, sha256 a46c915ad7d9c07f…

26: PHASE FCC_A1 %A 2 1 1 !
27: CONST FCC_A1 : CA% CU% : VA : !

CaCu-97Ais.tdb: FCC_A1, type code %A, sha256 649c86c7eee5fdbf…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : CA% CU% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase

HCP_A3 (Ca–Cu)

Id: phase:ca-cu: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 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ca-cu:hcp-a3
tdb: tdb:CaCu-96Ris-LB.tdb:HCP_A3, tdb:CaCu-97Ais.tdb:HCP_A3

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

CaCu-96Ris-LB.tdb: HCP_A3, type code %A, sha256 a46c915ad7d9c07f…

36: PHASE HCP_A3 %A 2 1 0.5 !
37: CONST HCP_A3 : CA CU : VA : !

CaCu-97Ais.tdb: HCP_A3, type code %A, sha256 649c86c7eee5fdbf…

40: PHASE HCP_A3 %A 2 1 0.5 !
41: CONST HCP_A3 : CA CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
assessment that models this phase

LIQUID (Ca–Cu)

Id: phase:ca-cu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 753.69–2500 K, x(Cu) 0–1
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ca-cu:liquid
paper: paper:10.1016/s0364-5916(96)00022-3:liquid
tdb: tdb:CaCu-96Ris-LB.tdb:LIQUID, tdb:CaCu-97Ais.tdb:LIQUID

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

CaCu-96Ris-LB.tdb: LIQUID, type code %, sha256 a46c915ad7d9c07f…

21: PHASE LIQUID:L % 1 1 !
22: CONST LIQUID:L : CA CU : !

CaCu-97Ais.tdb: LIQUID, type code %, sha256 649c86c7eee5fdbf…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : CA CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(96)00022-3 D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, Calphad, 20, 151-60(1996).
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}
}