Co–Er phases

11 phases (tier A 6, tier C 4, liquid 1); 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 · Co–Er system page · Markdown · field reference

Phases of the Co–Er system (11)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:co-er:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
CO17ER2 phase:co-er:co17er2	Ni17Th2 · hP38 · P6_3/mmc (194)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1646.07 K, x(Er) 0.10526–0.10526	8	1
CO2ER_C15 phase:co-er:co2er-c15	Cu2Mg · C15 · cF24 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1611.02 K, x(Er) 0.33333–0.33333	4	1
CO3ER phase:co-er:co3er	Ni3Pu · hR12 · R-3m (166)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1670.47 K, x(Er) 0.25–0.25	8	1
CO5ER_D2D phase:co-er:co5er-d2d	CaCu5 · D2_d · hP6 · P6/mmm (191)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1511.76–1609.71 K, x(Er) 0.16667–0.16667	6	1
CO7ER12 phase:co-er:co7er12	Co7Ho12 · mP38 · P2_1/c (14)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1096.34 K, x(Er) 0.63158–0.63158	6	1
CO7ER2 phase:co-er:co7er2	Co7Gd2 · hR18 · R-3m (166)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1625.17 K, x(Er) 0.22222–0.22222	6	1
COER3_D011 phase:co-er:coer3-d011	Fe3C · D0_11 · oP16 · Pnma (62)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1183.93 K, x(Er) 0.75–0.75	2	1
FCC_A1 phase:co-er:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 497.49–1774.81 K, x(Er) 0–0.0001	2	1
HCP_A3 phase:co-er:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2499.45 K, x(Er) 0–1	2	1
LIQUID phase:co-er:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1074.21–2500 K, x(Er) 0–1	22	1

BCC_A2 (Co–Er)

Id: phase:co-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:co-er:bcc-a2
tdb: tdb:CoEr-09Wan.tdb:BCC_A2

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

CoEr-09Wan.tdb: BCC_A2, type code %B, sha256 36ee4428d18320d8…

33: PHASE BCC_A2 %B 2 1 3 !
34: CONST BCC_A2 : CO ER : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase

CO17ER2 (Co–Er)

Id: phase:co-er:co17er2; status assigned
Structure: Ni17Th2 · hP38 · P6_3/mmc (194); type st:ni17th2-hp38; 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 (mp_oqmd_space_groups_differ, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Co 0.8947, Er 0.1053
Stability: stable in 1 of 1 calculated diagram(s): 300–1646.07 K, x(Er) 0.10526–0.10526
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:co17er2
paper: paper:10.1016/j.jallcom.2008.11.110:Co17Er2
tdb: tdb:CoEr-09Wan.tdb:CO17ER2

TDB models of CO17ER2 (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO17ER2, type code %A, sha256 36ee4428d18320d8…

43: PHASE CO17ER2 %A 2 17 2 !
44: CONST CO17ER2 : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

CO2ER_C15 (Co–Er)

Id: phase:co-er:co2er-c15; status assigned
Structure: Cu2Mg · C15 · cF24 · Fd-3m (227); type st:c15-cu2mg-cf24; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaaaur and oqmd-29233, space group 227
Stoichiometry: Co 0.6667, Er 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1611.02 K, x(Er) 0.33333–0.33333
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:co-er:co2er-c15
mp: mp:mp-aaaaaaur
oqmd: oqmd:oqmd-29233
paper: paper:10.1016/j.jallcom.2008.11.110:Co2Er
tdb: tdb:CoEr-09Wan.tdb:CO2ER_C15

TDB models of CO2ER_C15 (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO2ER_C15, type code %A, sha256 36ee4428d18320d8…

63: PHASE CO2ER_C15 %A 2 2 1 !
64: CONST CO2ER_C15 : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

CO3ER (Co–Er)

Id: phase:co-er:co3er; status assigned
Structure: Ni3Pu · hR12 · R-3m (166); type st:ni3pu-hr12; 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_166_matches_2_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Co 0.7500, Er 0.2500
Stability: stable in 1 of 1 calculated diagram(s): 300–1670.47 K, x(Er) 0.25–0.25
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:co3er
paper: paper:10.1016/j.jallcom.2008.11.110:Co3Er
tdb: tdb:CoEr-09Wan.tdb:CO3ER

TDB models of CO3ER (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO3ER, type code %A, sha256 36ee4428d18320d8…

58: PHASE CO3ER %A 2 3 1 !
59: CONST CO3ER : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

CO5ER_D2D (Co–Er)

Id: phase:co-er:co5er-d2d; status assigned
Structure: CaCu5 · D2_d · hP6 · P6/mmm (191); type st:d2-d-cacu5-hp6; tier A: standard phase name; confidence high
Stoichiometry: Co 0.8333, Er 0.1667
Stability: stable in 1 of 1 calculated diagram(s): 1511.76–1609.71 K, x(Er) 0.16667–0.16667
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:co5er-d2d
paper: paper:10.1016/j.jallcom.2008.11.110:Co5Er
tdb: tdb:CoEr-09Wan.tdb:CO5ER_D2D

TDB models of CO5ER_D2D (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO5ER_D2D, type code %A, sha256 36ee4428d18320d8…

48: PHASE CO5ER_D2D %A 2 5 1 !
49: CONST CO5ER_D2D : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

CO7ER12 (Co–Er)

Id: phase:co-er:co7er12; status assigned
Structure: Co7Ho12 · mP38 · P2_1/c (14); type st:co7ho12-mp38; 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 (no_on_hull_entry_in_oqmd, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Co 0.3684, Er 0.6316
Stability: stable in 1 of 1 calculated diagram(s): 300–1096.34 K, x(Er) 0.63158–0.63158
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:co7er12
paper: paper:10.1016/j.jallcom.2008.11.110:Co7Er12
tdb: tdb:CoEr-09Wan.tdb:CO7ER12

TDB models of CO7ER12 (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO7ER12, type code %A, sha256 36ee4428d18320d8…

68: PHASE CO7ER12 %A 2 7 12 !
69: CONST CO7ER12 : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

CO7ER2 (Co–Er)

Id: phase:co-er:co7er2; status assigned
Structure: Co7Gd2 · hR18 · R-3m (166); type st:co7gd2-hr18; 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 (no_on_hull_entry_in_both, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Co 0.7778, Er 0.2222
Stability: stable in 1 of 1 calculated diagram(s): 300–1625.17 K, x(Er) 0.22222–0.22222
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:co7er2
paper: paper:10.1016/j.jallcom.2008.11.110:Co7Er2
tdb: tdb:CoEr-09Wan.tdb:CO7ER2

TDB models of CO7ER2 (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: CO7ER2, type code %A, sha256 36ee4428d18320d8…

53: PHASE CO7ER2 %A 2 7 2 !
54: CONST CO7ER2 : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

COER3_D011 (Co–Er)

Id: phase:co-er:coer3-d011; status assigned
Structure: Fe3C · D0_11 · oP16 · Pnma (62); type st:d0-11-fe3c-op16; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaacpqny and oqmd-690190, space group 62
Stoichiometry: Co 0.2500, Er 0.7500
Stability: stable in 1 of 1 calculated diagram(s): 300–1183.93 K, x(Er) 0.75–0.75
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:co-er:coer3-d011
mp: mp:mp-aaacpqny
oqmd: oqmd:oqmd-690190
paper: paper:10.1016/j.jallcom.2008.11.110:CoEr3
tdb: tdb:CoEr-09Wan.tdb:COER3_D011

TDB models of COER3_D011 (1): PHASE and CONSTITUENT statements as written

CoEr-09Wan.tdb: COER3_D011, type code %A, sha256 36ee4428d18320d8…

73: PHASE COER3_D011 %A 2 1 3 !
74: CONST COER3_D011 : CO : ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

FCC_A1 (Co–Er)

Id: phase:co-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): 497.49–1774.81 K, x(Er) 0–0.0001
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:fcc-a1
paper: paper:10.1016/j.jallcom.2008.11.110:(αCo)
tdb: tdb:CoEr-09Wan.tdb:FCC_A1

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

CoEr-09Wan.tdb: FCC_A1, type code %A, sha256 36ee4428d18320d8…

28: PHASE FCC_A1 %A 2 1 1 !
29: CONST FCC_A1 : CO% ER : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

HCP_A3 (Co–Er)

Id: phase:co-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): 300–2499.45 K, x(Er) 0–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:hcp-a3
paper: paper:10.1016/j.jallcom.2008.11.110:(Er)
tdb: tdb:CoEr-09Wan.tdb:HCP_A3

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

CoEr-09Wan.tdb: HCP_A3, type code %A, sha256 36ee4428d18320d8…

38: PHASE HCP_A3 %A 2 1 0.5 !
39: CONST HCP_A3 : CO% ER% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
assessment that models this phase; reports values for this phase

LIQUID (Co–Er)

Id: phase:co-er:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1074.21–2500 K, x(Er) 0–1
Literature: 22 values (22 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-er:liquid
paper: paper:10.1016/j.jallcom.2008.11.110:L
tdb: tdb:CoEr-09Wan.tdb:LIQUID

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

CoEr-09Wan.tdb: LIQUID, type code %, sha256 36ee4428d18320d8…

23: PHASE LIQUID:L % 1 1 !
24: CONST LIQUID:L : CO ER : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2008.11.110 C.P. Wang, A.Q. Zheng, X.J. Liu, K. Ishida, Thermodynamic assessments of the Co–Er and V–Er systems, Journal of Alloys and Compounds 478, 197-201 (2009).
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}
}