Cu–Er phases

9 phases (tier A 5, tier C 1, liquid 1, needs_review 2); 8 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 · Cu–Er system page · Markdown · field reference

Phases of the Cu–Er system (9)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:cu-er:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
CU2ER phase:cu-er:cu2er	Hg2K · oI12 · Imma (74)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1174.08 K, x(Er) 0.33333–0.33333	10	1
CU5ER_C15B phase:cu-er:cu5er-c15b	AuBe5 · C15_b · cF24 · F-43m (216)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1273.15 K, x(Er) 0.16667–0.16667	4	1
CU7ER2 phase:cu-er:cu7er2		needs_review	stable in 1 of 1 calculated diagram(s): 1110.1–1209.96 K, x(Er) 0.22222–0.22222	4	1
CU9ER2 phase:cu-er:cu9er2		needs_review	stable in 1 of 1 calculated diagram(s): 300–1277.46 K, x(Er) 0.18182–0.18182	8	1
CUER_B2 phase:cu-er:cuer-b2	CsCl · B2 · cP2 · Pm-3m (221)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1319.48 K, x(Er) 0.5–0.5	4	1
FCC_A1 phase:cu-er:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1366.45 K, x(Er) 0–1e-05	2	1
HCP_A3 phase:cu-er:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2499.49 K, x(Er) 0.99863–1	2	1
LIQUID phase:cu-er:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1151.99–2500 K, x(Er) 0–1	16	1

BCC_A2 (Cu–Er)

Id: phase:cu-er: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 1 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:cu-er:bcc-a2
tdb: tdb:CuEr-08Zha.tdb:BCC_A2

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

CuEr-08Zha.tdb: BCC_A2, type code %B, sha256 2583547fba3f60fe…

34: PHASE BCC_A2 %B 2 1 3 !
35: CONST BCC_A2 : CU ER : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase

CU2ER (Cu–Er)

Id: phase:cu-er:cu2er; status assigned
Structure: Hg2K · oI12 · Imma (74); type st:hg2k-oi12; 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_74_matches_2_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Cu 0.6667, Er 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1174.08 K, x(Er) 0.33333–0.33333
Literature: 10 values (10 accepted) from 2 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:cu-er:cu2er
paper: paper:10.1016/j.calphad.2008.05.002:Cu2Er, paper:10.1016/j.calphad.2009.04.001:Cu2Er
tdb: tdb:CuEr-08Zha.tdb:CU2ER

TDB models of CU2ER (1): PHASE and CONSTITUENT statements as written

CuEr-08Zha.tdb: CU2ER, type code %, sha256 2583547fba3f60fe…

59: PHASE CU2ER % 2 2 1 !
60: CONST CU2ER : CU : ER : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2009.04.001 M. Palumbo, L. Battezzati, A. Pasturel, S. Gottlieb-Schönmeyer, W. Assmus, Thermodynamic and ab initio investigation of the Cu–Dy system, Calphad 33, 511-516 (2009).
reports values for this phase
doi:10.1016/j.jallcom.2004.08.062 S.V. Meschel, O.J. Kleppa, Thermochemistry of some binary alloys of copper with the lanthanide metals by high-temperature direct synthesis calorimetry, Journal of Alloys and Compounds 388, 91-97 (2005).
cited as the source of values for this phase

CU5ER_C15B (Cu–Er)

Id: phase:cu-er:cu5er-c15b; status assigned
Structure: AuBe5 · C15_b · cF24 · F-43m (216); type st:c15-b-aube5-cf24; tier A: standard phase name; confidence high
Stoichiometry: Cu 0.8333, Er 0.1667
Stability: stable in 1 of 1 calculated diagram(s): 300–1273.15 K, x(Er) 0.16667–0.16667
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:cu5er-c15b
paper: paper:10.1016/j.calphad.2008.05.002:Cu5Er
tdb: tdb:CuEr-08Zha.tdb:CU5ER_C15B

TDB models of CU5ER_C15B (1): PHASE and CONSTITUENT statements as written

CuEr-08Zha.tdb: CU5ER_C15B, type code %, sha256 2583547fba3f60fe…

44: PHASE CU5ER_C15B % 2 5 1 !
45: CONST CU5ER_C15B : CU : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

CU7ER2 (Cu–Er)

Id: phase:cu-er:cu7er2; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (literature_printed): (Cu7Er2) · ? — printed with a label mapped to this phase
Candidate (sgte_mmc2): (Cu7Er2) — Hallstedt 2025 mmc2 row for CU7ER2: Cu7Er2
Stoichiometry: Cu 0.7778, Er 0.2222
Stability: stable in 1 of 1 calculated diagram(s): 1110.1–1209.96 K, x(Er) 0.22222–0.22222
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:cu7er2
paper: paper:10.1016/j.calphad.2008.05.002:Cu7Er2
tdb: tdb:CuEr-08Zha.tdb:CU7ER2

TDB models of CU7ER2 (1): PHASE and CONSTITUENT statements as written

CuEr-08Zha.tdb: CU7ER2, type code %, sha256 2583547fba3f60fe…

54: PHASE CU7ER2 % 2 7 2 !
55: CONST CU7ER2 : CU : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

CU9ER2 (Cu–Er)

Id: phase:cu-er:cu9er2; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (literature_printed): (Cu9Er2) · ? — printed with a label mapped to this phase
Candidate (sgte_mmc2): (Cu9Er2) — Hallstedt 2025 mmc2 row for CU9ER2: Cu9Er2
Stoichiometry: Cu 0.8182, Er 0.1818
Stability: stable in 1 of 1 calculated diagram(s): 300–1277.46 K, x(Er) 0.18182–0.18182
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:cu9er2
paper: paper:10.1016/j.calphad.2008.05.002:Cu9Er2
tdb: tdb:CuEr-08Zha.tdb:CU9ER2

TDB models of CU9ER2 (1): PHASE and CONSTITUENT statements as written

CuEr-08Zha.tdb: CU9ER2, type code %, sha256 2583547fba3f60fe…

49: PHASE CU9ER2 % 2 9 2 !
50: CONST CU9ER2 : CU : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

CUER_B2 (Cu–Er)

Id: phase:cu-er:cuer-b2; status assigned
Structure: CsCl · B2 · cP2 · Pm-3m (221); type st:b2-cscl-cp2; tier A: standard phase name; confidence high
Stoichiometry: Cu 0.5000, Er 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–1319.48 K, x(Er) 0.5–0.5
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:cuer-b2
paper: paper:10.1016/j.calphad.2008.05.002:CuEr
tdb: tdb:CuEr-08Zha.tdb:CUER_B2

TDB models of CUER_B2 (1): PHASE and CONSTITUENT statements as written

CuEr-08Zha.tdb: CUER_B2, type code %, sha256 2583547fba3f60fe…

64: PHASE CUER_B2 % 2 1 1 !
65: CONST CUER_B2 : CU : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

FCC_A1 (Cu–Er)

Id: phase:cu-er: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): 300–1366.45 K, x(Er) 0–1e-05
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:fcc-a1
paper: paper:10.1016/j.calphad.2008.05.002:Fcc_Cu
tdb: tdb:CuEr-08Zha.tdb:FCC_A1

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

CuEr-08Zha.tdb: FCC_A1, type code %A, sha256 2583547fba3f60fe…

29: PHASE FCC_A1 %A 2 1 1 !
30: CONST FCC_A1 : CU% ER : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

HCP_A3 (Cu–Er)

Id: phase:cu-er: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 1 of 1 calculated diagram(s): 300–2499.49 K, x(Er) 0.99863–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:hcp-a3
paper: paper:10.1016/j.calphad.2008.05.002:Hcp_Er
tdb: tdb:CuEr-08Zha.tdb:HCP_A3

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

CuEr-08Zha.tdb: HCP_A3, type code %A, sha256 2583547fba3f60fe…

39: PHASE HCP_A3 %A 2 1 0.5 !
40: CONST HCP_A3 : CU ER% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
assessment that models this phase; reports values for this phase

LIQUID (Cu–Er)

Id: phase:cu-er:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1151.99–2500 K, x(Er) 0–1
Literature: 16 values (16 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-er:liquid
paper: paper:10.1016/j.calphad.2008.05.002:L
tdb: tdb:CuEr-08Zha.tdb:LIQUID

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

CuEr-08Zha.tdb: LIQUID, type code %, sha256 2583547fba3f60fe…

24: PHASE LIQUID:L % 1 1 !
25: CONST LIQUID:L : CU ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2008.05.002 L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Thermodynamic assessment of the Al–Cu–Er system, Calphad 32, 527-534 (2008).
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}
}