Fe–Ho phases

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

Phases of the Fe–Ho system (8)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:fe-ho:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1848.57 K, x(Ho) 0–0.00021	6	2
FCC_A1 phase:fe-ho:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 1184.8–1667.56 K, x(Ho) 0–0.00024	5	2
FE17HO2 phase:fe-ho:fe17ho2	Ni17Th2 · hP38 · P6_3/mmc (194)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 2 of 2 calculated diagram(s): 300–1619.69 K, x(Ho) 0.10526–0.10526	21	2
FE23HO6_D8A phase:fe-ho:fe23ho6-d8a	Mn23Th6 · D8_a · cF116 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1613.21 K, x(Ho) 0.2069–0.2069	12	2
FE2HO_C15 phase:fe-ho:fe2ho-c15	Cu2Mg · C15 · cF24 · Fd-3m (227)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1569.22 K, x(Ho) 0.33333–0.33333	9	2
FE3HO phase:fe-ho:fe3ho	Ni3Pu · hR12 · R-3m (166)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 2 of 2 calculated diagram(s): 300–1583.31 K, x(Ho) 0.25–0.25	13	2
HCP_A3 phase:fe-ho:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2499.48 K, x(Ho) 0.99282–1	5	2
LIQUID phase:fe-ho:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 1151.93–2500 K, x(Ho) 0–1	43	2

BCC_A2 (Fe–Ho)

Id: phase:fe-ho: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 2 of 2 calculated diagram(s): 300–1848.57 K, x(Ho) 0–0.00021
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-ho:bcc-a2
paper: paper:10.1016/j.jct.2013.11.037:δFe
tdb: tdb:FeHo-14Kar.tdb:BCC_A2, tdb:FeHo-19Xu.tdb:BCC_A2

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

FeHo-14Kar.tdb: BCC_A2, type code %B, sha256 41fa95b081c454d8…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : FE% HO% : VA : !

FeHo-19Xu.tdb: BCC_A2, type code %B, sha256 93b42acc4ccdb2f9…

36: PHASE BCC_A2 %B 2 1 3 !
37: CONST BCC_A2 : FE% HO% : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase

FCC_A1 (Fe–Ho)

Id: phase:fe-ho: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): 1184.8–1667.56 K, x(Ho) 0–0.00024
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:fe-ho:fcc-a1
paper: paper:10.1016/j.jct.2013.11.037:(γFe), paper:10.1016/j.jct.2013.11.037:γFe
tdb: tdb:FeHo-14Kar.tdb:FCC_A1, tdb:FeHo-19Xu.tdb:FCC_A1

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

FeHo-14Kar.tdb: FCC_A1, type code %A, sha256 41fa95b081c454d8…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : FE% HO : VA : !

FeHo-19Xu.tdb: FCC_A1, type code %A, sha256 93b42acc4ccdb2f9…

31: PHASE FCC_A1 %A 2 1 1 !
32: CONST FCC_A1 : FE% HO : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase

FE17HO2 (Fe–Ho)

Id: phase:fe-ho:fe17ho2; 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 (no_on_hull_entry_in_both, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Fe 0.8947, Ho 0.1053
Stability: stable in 2 of 2 calculated diagram(s): 300–1619.69 K, x(Ho) 0.10526–0.10526
Literature: 21 values (21 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-ho:fe17ho2
paper: paper:10.1016/j.jct.2013.11.037:Fe17Ho2
tdb: tdb:FeHo-14Kar.tdb:FE17HO2, tdb:FeHo-19Xu.tdb:FE17HO2

TDB models of FE17HO2 (2): PHASE and CONSTITUENT statements as written

FeHo-14Kar.tdb: FE17HO2, type code %A, sha256 41fa95b081c454d8…

47: PHASE FE17HO2 %A 2 17 2 !
48: CONST FE17HO2 : FE : HO : !

FeHo-19Xu.tdb: FE17HO2, type code %A, sha256 93b42acc4ccdb2f9…

46: PHASE FE17HO2 %A 2 17 2 !
47: CONST FE17HO2 : FE : HO : !

Example references (6 of 6; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase
doi:10.1016/j.jct.2012.09.021 A. Latini, V. Genova, J. Steiner, D. Gozzi, Thermodynamic properties of RE2Co17 intermetallics at high temperatures (RE = Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Lu), The Journal of Chemical Thermodynamics 57, 461-469 (2013).
cited as the source of values for this phase
doi:10.1021/je7003353 D. Gozzi, M. Iervolino, A. Latini, Thermodynamics of Fe-Rich Intermetallics along the Rare Earth Series, J. Chem. Eng. Data 52, 2350-2358 (2007).
cited as the source of values for this phase
doi:10.1109/tmag.1966.1065874 K. Strnat, G. Hoffer, A. Ray, Magnetic properties of rare--Earth--Iron intermetallic compounds, IEEE Trans. Magn. 2, 489-493 (1966).
cited as the source of values for this phase

FE23HO6_D8A (Fe–Ho)

Id: phase:fe-ho:fe23ho6-d8a; status assigned
Structure: Mn23Th6 · D8_a · cF116 · Fm-3m (225); type st:d8-a-mn23th6-cf116; tier A: standard phase name; confidence high
Stoichiometry: Fe 0.7931, Ho 0.2069
Stability: stable in 2 of 2 calculated diagram(s): 300–1613.21 K, x(Ho) 0.2069–0.2069
Literature: 12 values (12 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-ho:fe23ho6-d8a
paper: paper:10.1016/j.jct.2013.11.037:Fe23Ho6
tdb: tdb:FeHo-14Kar.tdb:FE23HO6_D8A, tdb:FeHo-19Xu.tdb:FE23HO6_D8A

TDB models of FE23HO6_D8A (2): PHASE and CONSTITUENT statements as written

FeHo-14Kar.tdb: FE23HO6_D8A, type code %A, sha256 41fa95b081c454d8…

52: PHASE FE23HO6_D8A %A 2 23 6 !
53: CONST FE23HO6_D8A : FE : HO : !

FeHo-19Xu.tdb: FE23HO6_D8A, type code %A, sha256 93b42acc4ccdb2f9…

51: PHASE FE23HO6_D8A %A 2 23 6 !
52: CONST FE23HO6_D8A : FE : HO : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase

FE2HO_C15 (Fe–Ho)

Id: phase:fe-ho:fe2ho-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-aaaaacwc and oqmd-31298, space group 227
Stoichiometry: Fe 0.6667, Ho 0.3333
Stability: stable in 2 of 2 calculated diagram(s): 300–1569.22 K, x(Ho) 0.33333–0.33333
Literature: 9 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (6): corpus: corpus:phase:fe-ho:fe2ho-c15
mp: mp:mp-aaaaacwc
oqmd: oqmd:oqmd-31298
paper: paper:10.1016/j.jct.2013.11.037:Fe2Ho
tdb: tdb:FeHo-14Kar.tdb:FE2HO_C15, tdb:FeHo-19Xu.tdb:FE2HO_C15

TDB models of FE2HO_C15 (2): PHASE and CONSTITUENT statements as written

FeHo-14Kar.tdb: FE2HO_C15, type code %A, sha256 41fa95b081c454d8…

62: PHASE FE2HO_C15 %A 2 2 1 !
63: CONST FE2HO_C15 : FE : HO : !

FeHo-19Xu.tdb: FE2HO_C15, type code %A, sha256 93b42acc4ccdb2f9…

61: PHASE FE2HO_C15 %A 2 2 1 !
62: CONST FE2HO_C15 : FE : HO : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase

FE3HO (Fe–Ho)

Id: phase:fe-ho:fe3ho; 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: Fe 0.7500, Ho 0.2500
Stability: stable in 2 of 2 calculated diagram(s): 300–1583.31 K, x(Ho) 0.25–0.25
Literature: 13 values (13 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-ho:fe3ho
paper: paper:10.1016/j.jct.2013.11.037:Fe3Ho
tdb: tdb:FeHo-14Kar.tdb:FE3HO, tdb:FeHo-19Xu.tdb:FE3HO

TDB models of FE3HO (2): PHASE and CONSTITUENT statements as written

FeHo-14Kar.tdb: FE3HO, type code %A, sha256 41fa95b081c454d8…

57: PHASE FE3HO %A 2 3 1 !
58: CONST FE3HO : FE : HO : !

FeHo-19Xu.tdb: FE3HO, type code %A, sha256 93b42acc4ccdb2f9…

56: PHASE FE3HO %A 2 3 1 !
57: CONST FE3HO : FE : HO : !

Example references (4 of 4; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase
doi:10.1016/0364-5916(83)90030-5 A.K. Niessen, F.R. de Boer, R. Boom, P.F. de Chatel, W.C.M. Mattens, A.R. Miedema, CALPHAD 7 (1983) 51–70.
cited as the source of values for this phase

HCP_A3 (Fe–Ho)

Id: phase:fe-ho: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 2 of 2 calculated diagram(s): 300–2499.48 K, x(Ho) 0.99282–1
Literature: 5 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-ho:hcp-a3
paper: paper:10.1016/j.jct.2013.11.037:(αHo)
tdb: tdb:FeHo-14Kar.tdb:HCP_A3, tdb:FeHo-19Xu.tdb:HCP_A3

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

FeHo-14Kar.tdb: HCP_A3, type code %A, sha256 41fa95b081c454d8…

42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : FE HO% : VA : !

FeHo-19Xu.tdb: HCP_A3, type code %A, sha256 93b42acc4ccdb2f9…

41: PHASE HCP_A3 %A 2 1 0.5 !
42: CONST HCP_A3 : FE HO% : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
cited as the source of values for this phase

LIQUID (Fe–Ho)

Id: phase:fe-ho:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1151.93–2500 K, x(Ho) 0–1
Literature: 43 values (42 accepted) from 1 papers
Interactive: phase registry entry

Names (6): corpus: corpus:phase:fe-ho:liquid
paper: paper:10.1016/j.jct.2013.11.037:L, paper:10.1016/j.jct.2013.11.037:Liq, paper:10.1016/j.jct.2013.11.037:liquid
tdb: tdb:FeHo-14Kar.tdb:LIQUID, tdb:FeHo-19Xu.tdb:LIQUID

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

FeHo-14Kar.tdb: LIQUID, type code %, sha256 41fa95b081c454d8…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : FE HO : !

FeHo-19Xu.tdb: LIQUID, type code %, sha256 93b42acc4ccdb2f9…

26: PHASE LIQUID:L % 1 1 !
27: CONST LIQUID:L : FE HO : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jct.2013.11.037 S. Kardellass, C. Servant, N. Selhaoui, A. Iddaoudi, M. Ait Amar, L. Bouirden, A thermodynamic assessment of the Iron+Holmium phase diagram, The Journal of Chemical Thermodynamics 74, 78-84 (2014).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2019.101646 L. Xu, J. Wang, S. Li, X.L. Chen, M.H. Rong, G.H. Rao, H.Y. Zhou, Calphad, 66, 101646(2019).
assessment that models this phase
doi:10.1007/bf03038385 G. J. Roe, T. J. O’Keefe, The Fe−Ho binary system, Metall Trans 1, 2565-2568 (1970).
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}
}