As–Cu phases

12 phases (tier A 6, liquid 2, needs_review 4); 10 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 · Markdown · field reference

Phases of the As–Cu system (12)
Phase	Structure	Basis	Stability (calculated)	TDB models
RHOMBOHEDRAL_A7 phase:as-cu:a7-rhombohedral	alpha-As · A7 · hR2 · R-3m (166)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1090 K, x(As) 1–1	2
BCC_A2 phase:as-cu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 2 calculated diagram(s)	2
CU12AS5_D03 phase:as-cu:cu12as5-d03		needs_review	stable in 1 of 1 calculated diagram(s): 573.12–982.59 K, x(As) 0.29412–0.29412	1
CU3AS phase:as-cu:cu3as		needs_review	stable in 1 of 1 calculated diagram(s): 300–1073.82 K, x(As) 0.25178–0.27711	1
CU3AS_D06 phase:as-cu:cu3as-d06		needs_review	stable in 1 of 1 calculated diagram(s): 300–1102.22 K, x(As) 0.25294–0.27659	1
CU7AS_A3 phase:as-cu:cu7as-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–620.29 K, x(As) 0.125–0.125	1
CU7AS3_D03 phase:as-cu:cu7as3-d03		needs_review	stable in 1 of 1 calculated diagram(s): 615.39–966.31 K, x(As) 0.3–0.3	1
CU8AS_A3 phase:as-cu:cu8as-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–597.77 K, x(As) 0.11111–0.11111	1
FCC_A1 phase:as-cu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2499.02 K, x(As) 0–0.06812	2
HCP_A3 phase:as-cu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 2 calculated diagram(s)	2
ION phase:as-cu:ion	liquid	liquid	stable in 1 of 1 calculated diagram(s): 872.04–2500 K, x(As) 0–0.99827	1
LIQUID phase:as-cu:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 802.79–2500 K, x(As) 0–1	2

RHOMBOHEDRAL_A7 (As–Cu)

Id: phase:as-cu:a7-rhombohedral; status assigned
Structure: alpha-As · A7 · hR2 · R-3m (166); type st:a7-alpha-as-hr2; tier A: standard phase name; confidence high
Stoichiometry: As 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 300–1090 K, x(As) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:as-cu:a7-rhombohedral
tdb: tdb:CuAs-01Uhl.tdb:RHOMBOHEDRAL_A7, tdb:CuAs-94Pei-LB.tdb:RHOMBOHEDRAL_A7

TDB models of RHOMBOHEDRAL_A7 (2): PHASE and CONSTITUENT statements as written

CuAs-01Uhl.tdb: RHOMBOHEDRAL_A7, type code %, sha256 37d4768fa49739e5…

47: PHASE RHOMBOHEDRAL_A7 % 1 1 !
48: CONST RHOMBOHEDRAL_A7 : AS : !

CuAs-94Pei-LB.tdb: RHOMBOHEDRAL_A7, type code %, sha256 8227f3feed69881f…

63: PHASE RHOMBOHEDRAL_A7 % 1 1 !
64: CONST RHOMBOHEDRAL_A7 : AS : !

Example references (2 of 2; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase
doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

BCC_A2 (As–Cu)

Id: phase:as-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: not stable in 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:as-cu:bcc-a2
tdb: tdb:CuAs-01Uhl.tdb:BCC_A2, tdb:CuAs-94Pei-LB.tdb:BCC_A2

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

CuAs-01Uhl.tdb: BCC_A2, type code %B, sha256 37d4768fa49739e5…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : AS CU : VA : !

CuAs-94Pei-LB.tdb: BCC_A2, type code %B, sha256 8227f3feed69881f…

53: PHASE BCC_A2 %B 2 1 3 !
54: CONST BCC_A2 : AS CU : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase
doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

CU12AS5_D03 (As–Cu)

Id: phase:as-cu:cu12as5-d03; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:stoichiometry_contradicts_D0_3; stoichiometry_contradicts_D0_3:CuAs-94Pei-LB.tdb
Candidate (name_token): BiF3 · D0_3 · cF16 · Fm-3m (225) — Strukturbericht/word 'D03' in the TDB name
Candidate (sgte_mmc2): BiF3 · D0_3 · cF16 · Fm-3m (225) — Hallstedt 2025 mmc2 row for CU12AS5_D03: Cu12As5
Candidate (tdb_comment): BiF3 · cF16 · Fm-3m — CuAs-94Pei-LB.tdb: 'Prototype BiF3 (cF16, Fm-3m)'
Stoichiometry: As 0.2941, Cu 0.7059
Stability: stable in 1 of 1 calculated diagram(s): 573.12–982.59 K, x(As) 0.29412–0.29412
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu12as5-d03
tdb: tdb:CuAs-94Pei-LB.tdb:CU12AS5_D03

TDB models of CU12AS5_D03 (1): PHASE and CONSTITUENT statements as written

CuAs-94Pei-LB.tdb: CU12AS5_D03, type code %, sha256 8227f3feed69881f…

78: PHASE CU12AS5_D03 % 2 12 5 !
79: CONST CU12AS5_D03 : CU : AS : !

Example references (1 of 1; assessments first):

doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

CU3AS (As–Cu)

Id: phase:as-cu:cu3as; status needs_review
No structure assigned. Why: assessment_declared_compound_differs_from_site_ratios; no_structure_token; off_stoichiometric_model
Candidate (sgte_mmc2): HoH3 · hP24 · P-3c1 (165) — Hallstedt 2025 mmc2 row for CU3AS: Cu3As
Candidate (tdb_comment): HoH3 · hP24 · P-3c1 — CuAs-01Uhl.tdb: 'Prototype HoH3 (hP24, P-3c1), prototype Cu3As suggested in LB binary'
Stability: stable in 1 of 1 calculated diagram(s): 300–1073.82 K, x(As) 0.25178–0.27711
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu3as
tdb: tdb:CuAs-01Uhl.tdb:CU3AS

TDB models of CU3AS (1): PHASE and CONSTITUENT statements as written

CuAs-01Uhl.tdb: CU3AS, type code %, sha256 37d4768fa49739e5…

57: PHASE CU3AS % 2 3 1.15 !
58: CONST CU3AS : CU : AS% CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase

CU3AS_D06 (As–Cu)

Id: phase:as-cu:cu3as-d06; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:D06; no_structure_token
Candidate (tdb_comment): HoH3 · hP24 · P-3c1 — CuAs-94Pei-LB.tdb: 'Prototype HoH3 (hP24, P-3c1), prototype Cu3As suggested in LB binary'
Stability: stable in 1 of 1 calculated diagram(s): 300–1102.22 K, x(As) 0.25294–0.27659
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu3as-d06
tdb: tdb:CuAs-94Pei-LB.tdb:CU3AS_D06

TDB models of CU3AS_D06 (1): PHASE and CONSTITUENT statements as written

CuAs-94Pei-LB.tdb: CU3AS_D06, type code %, sha256 8227f3feed69881f…

73: PHASE CU3AS_D06 % 2 3 1 !
74: CONST CU3AS_D06 : CU VA : AS : !

Example references (1 of 1; assessments first):

doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

CU7AS_A3 (As–Cu)

Id: phase:as-cu:cu7as-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stoichiometry: As 0.1250, Cu 0.8750
Stability: stable in 1 of 1 calculated diagram(s): 300–620.29 K, x(As) 0.125–0.125
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu7as-a3
tdb: tdb:CuAs-01Uhl.tdb:CU7AS_A3

TDB models of CU7AS_A3 (1): PHASE and CONSTITUENT statements as written

CuAs-01Uhl.tdb: CU7AS_A3, type code %, sha256 37d4768fa49739e5…

52: PHASE CU7AS_A3 % 2 7 1 !
53: CONST CU7AS_A3 : CU : AS : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase

CU7AS3_D03 (As–Cu)

Id: phase:as-cu:cu7as3-d03; status needs_review
No structure assigned. Why: stoichiometry_contradicts_D0_3:CuAs-01Uhl.tdb
Candidate (name_token): BiF3 · D0_3 · cF16 · Fm-3m (225) — Strukturbericht/word 'D03' in the TDB name
Candidate (tdb_comment): BiF3 · cF16 · Fm-3m — CuAs-01Uhl.tdb: 'Prototype BiF3 (cF16, Fm-3m)'
Stoichiometry: As 0.3000, Cu 0.7000
Stability: stable in 1 of 1 calculated diagram(s): 615.39–966.31 K, x(As) 0.3–0.3
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu7as3-d03
tdb: tdb:CuAs-01Uhl.tdb:CU7AS3_D03

TDB models of CU7AS3_D03 (1): PHASE and CONSTITUENT statements as written

CuAs-01Uhl.tdb: CU7AS3_D03, type code %, sha256 37d4768fa49739e5…

62: PHASE CU7AS3_D03 % 2 7 3 !
63: CONST CU7AS3_D03 : CU : AS : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase

CU8AS_A3 (As–Cu)

Id: phase:as-cu:cu8as-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stoichiometry: As 0.1111, Cu 0.8889
Stability: stable in 1 of 1 calculated diagram(s): 300–597.77 K, x(As) 0.11111–0.11111
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:cu8as-a3
tdb: tdb:CuAs-94Pei-LB.tdb:CU8AS_A3

TDB models of CU8AS_A3 (1): PHASE and CONSTITUENT statements as written

CuAs-94Pei-LB.tdb: CU8AS_A3, type code %, sha256 8227f3feed69881f…

68: PHASE CU8AS_A3 % 2 8 1 !
69: CONST CU8AS_A3 : CU : AS : !

Example references (1 of 1; assessments first):

doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

FCC_A1 (As–Cu)

Id: phase:as-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): 300–2499.02 K, x(As) 0–0.06812
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:as-cu:fcc-a1
tdb: tdb:CuAs-01Uhl.tdb:FCC_A1, tdb:CuAs-94Pei-LB.tdb:FCC_A1

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

CuAs-01Uhl.tdb: FCC_A1, type code %A, sha256 37d4768fa49739e5…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : AS CU : VA : !

CuAs-94Pei-LB.tdb: FCC_A1, type code %A, sha256 8227f3feed69881f…

48: PHASE FCC_A1 %A 2 1 1 !
49: CONST FCC_A1 : AS CU : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase
doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

HCP_A3 (As–Cu)

Id: phase:as-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:as-cu:hcp-a3
tdb: tdb:CuAs-01Uhl.tdb:HCP_A3, tdb:CuAs-94Pei-LB.tdb:HCP_A3

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

CuAs-01Uhl.tdb: HCP_A3, type code %A, sha256 37d4768fa49739e5…

42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : AS CU : VA : !

CuAs-94Pei-LB.tdb: HCP_A3, type code %A, sha256 8227f3feed69881f…

58: PHASE HCP_A3 %A 2 1 0.5 !
59: CONST HCP_A3 : AS CU : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase
doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

ION (As–Cu)

Id: phase:as-cu:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 872.04–2500 K, x(As) 0–0.99827
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-cu:ion
tdb: tdb:CuAs-94Pei-LB.tdb:ION

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

CuAs-94Pei-LB.tdb: ION, type code %, sha256 8227f3feed69881f…

43: PHASE ION:Y % 2 1 1 !
44: CONST ION:Y : CU+1 : AS-3 VA AS : !

Example references (1 of 1; assessments first):

doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
assessment that models this phase

LIQUID (As–Cu)

Id: phase:as-cu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 802.79–2500 K, x(As) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:as-cu:liquid
tdb: tdb:CuAs-01Uhl.tdb:LIQUID, tdb:CuAs-94Pei-LB.tdb:LIQUID

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

CuAs-01Uhl.tdb: LIQUID, type code %, sha256 37d4768fa49739e5…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : AS CU : !

CuAs-94Pei-LB.tdb: LIQUID, type code %, sha256 8227f3feed69881f…

40: PHASE LIQUID:L % 1 1 !
41: CONST LIQUID:L : CU AS : !

Example references (2 of 2; assessments first):

doi:10.1016/S0364-5916(01)00034-7 S. Uhland, H. Lechtman, L. Kaufman, Calphad, 25, 109-24(2001).
assessment that models this phase
doi:10.1515/ijmr-1994-850305 B. Pei, B. Bjorkman, B. Jansson, B. Sundman, Z. Metallkd., 85, 178-84(1994).
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}
}