Cu–Er system

29 accepted literature values from 2 paper(s) (experimental 13, model 8, DFT 3, unspecified 5); 1 calculated phase diagram(s). 6 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: JSON · CSV · interactive explorer · interactive phase diagram · phases (9) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	13
model	8
DFT	3
unspecified	5

Accepted values by property group
Property group	Values
invariant reaction	12
phase transition	4
formation	8
crystal structure	5

Calculated phase diagrams

Binary phase diagrams calculated with pycalphad 0.11.2 from the SGTE binary collection (Hallstedt 2025, CC BY 4.0). Evidence class: model.

Assessments with a calculated phase diagram
TDB file	Assessment	SHA-256	Links
CuEr-08Zha.tdb	L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia, Z.P. Jin, Calphad, 32, 527-34(2008). doi:10.1016/j.calphad.2008.05.002	`2583547fba3f60fe38630f8bc63084e62f900c102043ba35a0bd5585451a2021`	viewer · TDB · JSON

Calculated three-phase invariants (model, mole fraction of the second component)
TDB file	T (K)	Phases at the invariant
CuEr-08Zha.tdb	1273.15	LIQUID (x(Er) 0.16315) + CU5ER_C15B (x(Er) 0.16667) + CU9ER2 (x(Er) 0.18182)
CuEr-08Zha.tdb	1273.14	LIQUID (x(Er) 0.16342) + CU5ER_C15B (x(Er) 0.16667) + CU9ER2 (x(Er) 0.18182)
CuEr-08Zha.tdb	1273.14	LIQUID (x(Er) 0.16357) + CU5ER_C15B (x(Er) 0.16667) + CU9ER2 (x(Er) 0.18182)
CuEr-08Zha.tdb	1209.96	CU9ER2 (x(Er) 0.18182) + CU7ER2 (x(Er) 0.22222) + LIQUID (x(Er) 0.25866)
CuEr-08Zha.tdb	1209.95	CU9ER2 (x(Er) 0.18182) + CU7ER2 (x(Er) 0.22222) + LIQUID (x(Er) 0.25887)
CuEr-08Zha.tdb	1173.25	CU2ER (x(Er) 0.33333) + LIQUID (x(Er) 0.34406) + CUER_B2 (x(Er) 0.5)
CuEr-08Zha.tdb	1173.25	CU2ER (x(Er) 0.33333) + LIQUID (x(Er) 0.34403) + CUER_B2 (x(Er) 0.5)
CuEr-08Zha.tdb	1173.25	CU2ER (x(Er) 0.33333) + LIQUID (x(Er) 0.34431) + CUER_B2 (x(Er) 0.5)
CuEr-08Zha.tdb	1161.17	FCC_A1 (x(Er) 1.000e-5) + LIQUID (x(Er) 0.08126) + CU5ER_C15B (x(Er) 0.16667)
CuEr-08Zha.tdb	1161.17	FCC_A1 (x(Er) 1.000e-5) + LIQUID (x(Er) 0.08122) + CU5ER_C15B (x(Er) 0.16667)
CuEr-08Zha.tdb	1161.17	FCC_A1 (x(Er) 1.000e-5) + LIQUID (x(Er) 0.08118) + CU5ER_C15B (x(Er) 0.16667)
CuEr-08Zha.tdb	1161.17	FCC_A1 (x(Er) 1.000e-5) + LIQUID (x(Er) 0.08118) + CU5ER_C15B (x(Er) 0.16667)
CuEr-08Zha.tdb	1160.65	CU7ER2 (x(Er) 0.22222) + LIQUID (x(Er) 0.29349) + CU2ER (x(Er) 0.33333)
CuEr-08Zha.tdb	1160.65	CU7ER2 (x(Er) 0.22222) + LIQUID (x(Er) 0.29359) + CU2ER (x(Er) 0.33333)
CuEr-08Zha.tdb	1151.99	CUER_B2 (x(Er) 0.5) + LIQUID (x(Er) 0.69873) + HCP_A3 (x(Er) 0.99866)
CuEr-08Zha.tdb	1151.99	CUER_B2 (x(Er) 0.5) + LIQUID (x(Er) 0.69878) + HCP_A3 (x(Er) 0.99866)
CuEr-08Zha.tdb	1110.1	CU9ER2 (x(Er) 0.18182) + CU7ER2 (x(Er) 0.22222) + CU2ER (x(Er) 0.33333)

Convex hulls: Materials Project DFT hull · OQMD DFT hull

Invariant reactions (literature)

Invariant reactions reported in the literature for the Cu–Er system (12)
T (K)	Reaction / phases	Compositions (mole fraction)	Class	Source	Location
1278	peritectic: L + Cu9Er2 -> Cu5Er	L: Er 0.162; Cu9Er2: Er 0.181818; Cu5Er: Er 0.166667	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 3 report
1273	peritectic: L + Cu9Er2 -> Cu5Er	L: Er 0.164; Cu9Er2: Er 0.181818; Cu5Er: Er 0.166667	model	[1] Zhang 2008	Table 3, p. 6, row 4 report
1213	peritectic: L + Cu9Er2 -> Cu7Er2	Cu9Er2: Er 0.181818; Cu7Er2: Er 0.222222	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 7 report
1210	peritectic: L + Cu9Er2 -> Cu7Er2	L: Er 0.259; Cu9Er2: Er 0.181818; Cu7Er2: Er 0.222222	model	[1] Zhang 2008	Table 3, p. 6, row 8 report
1178	eutectic: L -> Cu2Er + CuEr	L: Er 0.385; Cu2Er: Er 0.333333; CuEr: Er 0.5	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 11 report
1173	eutectic: L -> Cu2Er + CuEr	L: Er 0.344; Cu2Er: Er 0.333333; CuEr: Er 0.5	model	[1] Zhang 2008	Table 3, p. 6, row 12 report
1168	eutectic: L -> Fcc_Cu + Cu5Er	L: Er 0.095; Cu5Er: Er 0.166667	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 1 report
1162	eutectic: L -> Fcc_Cu + Cu5Er	L: Er 0.0815; Cu5Er: Er 0.166667	model	[1] Zhang 2008	Table 3, p. 6, row 2 report
1160	eutectic: L -> Cu7Er2 + Cu2Er	L: Er 0.293; Cu7Er2: Er 0.222222; Cu2Er: Er 0.333333	model	[1] Zhang 2008	Table 3, p. 6, row 10 report
1158	eutectic: L -> Cu7Er2 + Cu2Er	L: Er 0.3; Cu7Er2: Er 0.222222; Cu2Er: Er 0.333333	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 9 report
1153	eutectic: L -> CuEr + Hcp_Er	L: Er 0.695; CuEr: Er 0.5	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 15 report
1152	eutectic: L -> CuEr + Hcp_Er	L: Er 0.699; CuEr: Er 0.5	model	[1] Zhang 2008	Table 3, p. 6, row 16 report

Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from dft_parity.json.

Enthalpies of formation, Cu–Er system (8)
Phase	Compound	Value	T (K)	Class	MP DFT (kJ/mol-atom)	OQMD DFT (kJ/mol-atom)	Source	Location
Cu2Er		-29.1 kJ/mol-atom	0	DFT			[2] Palumbo 2009	Table 2, p. 4, row 15 report
Cu2Er	Cu2Er	-27 kJ/mol-atom	298.15	experimental	-27.328 (mp-aaacgigt)	-27.311 (oqmd-2026377)	[2] Palumbo 2009 cites Meschel 2005 doi	Table 2, p. 4, row 17 report
Cu2Er	Cu2Er	-17.2 kJ/mol-atom	298.15	experimental	-27.328 (mp-aaacgigt)	-27.311 (oqmd-2026377)	[2] Palumbo 2009 cites Sommer 2009	Table 2, p. 4, row 16 report
Cu5Er		-20.1 kJ/mol-atom	0	DFT			[2] Palumbo 2009	Table 2, p. 4, row 12 report
Cu5Er	Cu5Er	-18.4 kJ/mol-atom	298.15	experimental	-18.819 (mp-aaaabtgd)	-18.957 (oqmd-1366368)	[2] Palumbo 2009 cites Meschel 2005 doi	Table 2, p. 4, row 14 report
Cu5Er	Cu5Er	-10.7 kJ/mol-atom	298.15	experimental	-18.819 (mp-aaaabtgd)	-18.957 (oqmd-1366368)	[2] Palumbo 2009 cites Sommer 2009	Table 2, p. 4, row 13 report
CuEr		-28.5 kJ/mol-atom	0	DFT			[2] Palumbo 2009	Table 2, p. 4, row 18 report
CuEr	CuEr	-14.6 kJ/mol-atom	298.15	experimental	-26.362 (mp-aaaaacxf)	-26.996 (oqmd-1376938)	[2] Palumbo 2009 cites Sommer 2009	Table 2, p. 4, row 19 report

Other properties

Phase transition (4)

Phase transition, Cu–Er system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Phase transition	1278 K	1278	congruent melting: L -> Cu9Er2 L: Er 0.181818; Cu9Er2: Er 0.181818	model	[1] Zhang 2008	Table 3, p. 6, row 6 report
Phase transition	1283 K	1283	congruent melting: L -> Cu9Er2 L: Er 0.181818; Cu9Er2: Er 0.181818	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 5 report
Phase transition	1319 K	1319	congruent melting: L -> Cu9Er2 L: Er 0.181818; Cu9Er2: Er 0.181818	model	[1] Zhang 2008	Table 3, p. 6, row 14 report
Phase transition	1328 K	1328	congruent melting: L -> Cu9Er2 L: Er 0.181818; Cu9Er2: Er 0.181818	experimental	[1] Zhang 2008 cites Buschow 1970	Table 3, p. 6, row 13 report

Crystal structure (5)

Crystal structure, Cu–Er system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Lattice a	4.275 Å	298.15	Cu2Er alloy: Cu 0.666667, Er 0.333333	unspecified	[1] Zhang 2008	Table 1, p. 3, row 16 report
Lattice a	7.003 Å	298.15	Cu5Er alloy: Cu 0.833333, Er 0.166667	unspecified	[1] Zhang 2008	Table 1, p. 3, row 13 report
Lattice a	3.425 Å	298.15	CuEr alloy: Cu 0.5, Er 0.5	unspecified	[1] Zhang 2008	Table 1, p. 3, row 17 report
Lattice b	6.726 Å	298.15	Cu2Er alloy: Cu 0.666667, Er 0.333333	unspecified	[1] Zhang 2008	Table 1, p. 3, row 16 report
Lattice c	7.265 Å	298.15	Cu2Er alloy: Cu 0.666667, Er 0.333333	unspecified	[1] Zhang 2008	Table 1, p. 3, row 16 report

Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

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). doi:10.1016/j.calphad.2008.05.002
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). doi:10.1016/j.calphad.2009.04.001

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735569
R. Arróyave, J. Saal, D. Shin, ORCHID-Diagrams: calculated binary phase diagrams (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735859
R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735891
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 the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); 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). 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_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_phase_diagrams_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Diagrams: calculated binary phase diagrams}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735859},
  url       = {https://doi.org/10.5281/zenodo.23735859}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@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}
}