Cu–Eu phases

8 phases (tier A 5, tier C 2, liquid 1); 7 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–Eu system page · Markdown · field reference

Phases of the Cu–Eu system (8)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:cu-eu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2500 K, x(Eu) 0.99932–1	2	1
CU2EU phase:cu-eu:cu2eu	Hg2K · oI12 · Imma (74)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–865.88 K, x(Eu) 0.33333–0.33333	4	1
CU5EU_D2D phase:cu-eu:cu5eu-d2d	CaCu5 · D2_d · hP6 · P6/mmm (191)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1114.73 K, x(Eu) 0.16667–0.16667	6	1
CUEU_B27 phase:cu-eu:cueu-b27	FeB · B27 · oP8 · Pnma (62)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–801.33 K, x(Eu) 0.5–0.5	4	1
CUEU2 phase:cu-eu:cueu2	Ca2Cu · oP12 · Pnma (62)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–727.82 K, x(Eu) 0.66667–0.66667	4	1
FCC_A1 phase:cu-eu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1407.52 K, x(Eu) 0–0	2	1
HCP_A3 phase:cu-eu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
LIQUID phase:cu-eu:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 724.22–2500 K, x(Eu) 0–1	12	1

BCC_A2 (Cu–Eu)

Id: phase:cu-eu: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): 300–2500 K, x(Eu) 0.99932–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-eu:bcc-a2
paper: paper:10.1016/j.calphad.2006.11.003:BCC(Eu)
tdb: tdb:CuEu-07Zha.tdb:BCC_A2

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

CuEu-07Zha.tdb: BCC_A2, type code %B, sha256 4a0bb1c43d7e14de…

40: PHASE BCC_A2 %B 2 1 3 !
41: CONST BCC_A2 : CU EU% : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

CU2EU (Cu–Eu)

Id: phase:cu-eu:cu2eu; 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, Eu 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–865.88 K, x(Eu) 0.33333–0.33333
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-eu:cu2eu
paper: paper:10.1016/j.calphad.2006.11.003:Cu2Eu
tdb: tdb:CuEu-07Zha.tdb:CU2EU

TDB models of CU2EU (1): PHASE and CONSTITUENT statements as written

CuEu-07Zha.tdb: CU2EU, type code %, sha256 4a0bb1c43d7e14de…

55: PHASE CU2EU % 2 2 1 !
56: CONST CU2EU : CU : EU : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

CU5EU_D2D (Cu–Eu)

Id: phase:cu-eu:cu5eu-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-aaaaadbm and oqmd-18820, space group 191
Stoichiometry: Cu 0.8333, Eu 0.1667
Stability: stable in 1 of 1 calculated diagram(s): 300–1114.73 K, x(Eu) 0.16667–0.16667
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:cu-eu:cu5eu-d2d
mp: mp:mp-aaaaadbm
oqmd: oqmd:oqmd-18820
paper: paper:10.1016/j.calphad.2006.11.003:Cu5Eu
tdb: tdb:CuEu-07Zha.tdb:CU5EU_D2D

TDB models of CU5EU_D2D (1): PHASE and CONSTITUENT statements as written

CuEu-07Zha.tdb: CU5EU_D2D, type code %, sha256 4a0bb1c43d7e14de…

50: PHASE CU5EU_D2D % 2 5 1 !
51: CONST CU5EU_D2D : CU : EU : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

CUEU_B27 (Cu–Eu)

Id: phase:cu-eu:cueu-b27; status assigned
Structure: FeB · B27 · oP8 · Pnma (62); type st:b27-feb-op8; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaacjwut and oqmd-29636, space group 62
Stoichiometry: Cu 0.5000, Eu 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–801.33 K, x(Eu) 0.5–0.5
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:cu-eu:cueu-b27
mp: mp:mp-aaacjwut
oqmd: oqmd:oqmd-29636
paper: paper:10.1016/j.calphad.2006.11.003:CuEu
tdb: tdb:CuEu-07Zha.tdb:CUEU_B27

TDB models of CUEU_B27 (1): PHASE and CONSTITUENT statements as written

CuEu-07Zha.tdb: CUEU_B27, type code %, sha256 4a0bb1c43d7e14de…

60: PHASE CUEU_B27 % 2 1 1 !
61: CONST CUEU_B27 : CU : EU : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

CUEU2 (Cu–Eu)

Id: phase:cu-eu:cueu2; 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: Cu 0.3333, Eu 0.6667
Stability: stable in 1 of 1 calculated diagram(s): 300–727.82 K, x(Eu) 0.66667–0.66667
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-eu:cueu2
paper: paper:10.1016/j.calphad.2006.11.003:CuEu2
tdb: tdb:CuEu-07Zha.tdb:CUEU2

TDB models of CUEU2 (1): PHASE and CONSTITUENT statements as written

CuEu-07Zha.tdb: CUEU2, type code %, sha256 4a0bb1c43d7e14de…

65: PHASE CUEU2 % 2 1 2 !
66: CONST CUEU2 : CU : EU : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

FCC_A1 (Cu–Eu)

Id: phase:cu-eu: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): 300–1407.52 K, x(Eu) 0–0
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-eu:fcc-a1
paper: paper:10.1016/j.calphad.2006.11.003:FCC(Cu)
tdb: tdb:CuEu-07Zha.tdb:FCC_A1

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

CuEu-07Zha.tdb: FCC_A1, type code %A, sha256 4a0bb1c43d7e14de…

35: PHASE FCC_A1 %A 2 1 1 !
36: CONST FCC_A1 : CU% EU : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of values for this phase

HCP_A3 (Cu–Eu)

Id: phase:cu-eu: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: Cu 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:cu-eu:hcp-a3
tdb: tdb:CuEu-07Zha.tdb:HCP_A3

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

CuEu-07Zha.tdb: HCP_A3, type code %A, sha256 4a0bb1c43d7e14de…

45: PHASE HCP_A3 %A 2 1 0.5 !
46: CONST HCP_A3 : CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase

LIQUID (Cu–Eu)

Id: phase:cu-eu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 724.22–2500 K, x(Eu) 0–1
Literature: 12 values (12 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-eu:liquid
paper: paper:10.1016/j.calphad.2006.11.003:L
tdb: tdb:CuEu-07Zha.tdb:LIQUID

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

CuEu-07Zha.tdb: LIQUID, type code %, sha256 4a0bb1c43d7e14de…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : CU EU : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2006.11.003 L.G. Zhang, L.B. Liu, H.S. Liu, Z.P. Jin, Thermodynamic assessment of Cu–Eu and Cu–Yb system, Calphad 31, 264-268 (2007).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(85)90378-9 G.A. Costa, E.A. Franceschi, A. Tawansi, Phase equilibria in the EuCu system, Journal of the Less Common Metals 106, 175-182 (1985).
cited as the source of 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}
}