H–Sm phases

9 phases (tier A 4, tier C 1, liquid 1, gas 2, needs_review 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 · H–Sm system page · Markdown · field reference

Phases of the H–Sm system (9)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:h-sm:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1181.24–1388.54 K, x(H) 0–0.30379	2	1
FCC_A1 phase:h-sm:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
GAS phase:h-sm:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300.77–2500 K, x(H) 0–1	1	1
H2GAS phase:h-sm:h2gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–1025.77 K, x(H) 1–1	2	1
HCP_A3 phase:h-sm:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 788.63–1275.5 K, x(H) 0–0.24289	3	1
LIQUID phase:h-sm:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1345–2066.83 K, x(H) 0–0.34012	2	1
RHOMB_C19 phase:h-sm:rhomb-c19		needs_review	stable in 1 of 1 calculated diagram(s): 300–1006.98 K, x(H) 0–0.08519	2	1
SMH2_C1 phase:h-sm:smh2-c1	CaF2 · C1 · cF12 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1493.46 K, x(H) 0.62188–0.71672	7	1
SMH3 phase:h-sm:smh3	HoH3 · hP24 · P-3c1 (165)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–580.77 K, x(H) 0.73094–0.74986	2	1

BCC_A2 (H–Sm)

Id: phase:h-sm: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): 1181.24–1388.54 K, x(H) 0–0.30379
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:bcc-a2
paper: paper:10.1016/s0925-8388(01)01990-9:(γ-Sm)
tdb: tdb:SmH-02Zin.tdb:BCC_A2

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

SmH-02Zin.tdb: BCC_A2, type code %B, sha256 3daabda9c80bc264…

44: PHASE BCC_A2 %B 2 1 1 !
45: CONST BCC_A2 : SM : H VA% : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase

FCC_A1 (H–Sm)

Id: phase:h-sm:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; 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:h-sm:fcc-a1
tdb: tdb:SmH-02Zin.tdb:FCC_A1

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

SmH-02Zin.tdb: FCC_A1, type code %A, sha256 3daabda9c80bc264…

38: PHASE FCC_A1 %A 2 1 1 !
39: CONST FCC_A1 : SM : H VA% : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase

GAS (H–Sm)

Id: phase:h-sm:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300.77–2500 K, x(H) 0–1
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:gas
paper: paper:10.1016/s0925-8388(01)01990-9:H2
tdb: tdb:SmH-02Zin.tdb:GAS

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

SmH-02Zin.tdb: GAS, type code %, sha256 3daabda9c80bc264…

68: PHASE GAS:G % 1 1 !
69: CONST GAS:G : H H2 SM : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase

H2GAS (H–Sm)

Id: phase:h-sm:h2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1025.77 K, x(H) 1–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:h2gas
paper: paper:10.1016/s0925-8388(01)01990-9:H2
tdb: tdb:SmH-02Zin.tdb:H2GAS

TDB models of H2GAS (1): PHASE and CONSTITUENT statements as written

SmH-02Zin.tdb: H2GAS, type code %, sha256 3daabda9c80bc264…

71: PHASE H2GAS % 1 1 !
72: CONST H2GAS : H2 : !

Example references (3 of 3; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(74)90025-3 M.H. Mintz, Z. Hadari, M. Bixon, Phase transformations in some rare earth-hydrogen systems, Journal of the Less Common Metals 37, 331-335 (1974).
cited as the source of values for this phase
doi:10.1016/0022-5088(76)90006-0 M.H. Mintz, D. Hiershler, Z. Hadari, Systematic study of the h.c.p. ⇌ f.c.c. transitions in the heavier LnH2-LnH3 systems, Journal of the Less Common Metals 48, 241-249 (1976).
cited as the source of values for this phase

HCP_A3 (H–Sm)

Id: phase:h-sm: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): 788.63–1275.5 K, x(H) 0–0.24289
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:hcp-a3
paper: paper:10.1016/s0925-8388(01)01990-9:(β-Sm)
tdb: tdb:SmH-02Zin.tdb:HCP_A3

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

SmH-02Zin.tdb: HCP_A3, type code %A, sha256 3daabda9c80bc264…

50: PHASE HCP_A3 %A 2 1 1 !
51: CONST HCP_A3 : SM : H VA% : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase

LIQUID (H–Sm)

Id: phase:h-sm:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1345–2066.83 K, x(H) 0–0.34012
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:liquid
paper: paper:10.1016/s0925-8388(01)01990-9:L
tdb: tdb:SmH-02Zin.tdb:LIQUID

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

SmH-02Zin.tdb: LIQUID, type code %, sha256 3daabda9c80bc264…

33: PHASE LIQUID:L % 2 1 1 !
34: CONST LIQUID:L : SM : H VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase

RHOMB_C19 (H–Sm)

Id: phase:h-sm:rhomb-c19; status needs_review
No structure assigned. Why: site_ratios_contradict_C19:SmH-02Zin.tdb
Candidate (name_token): CdCl2 · C19 · hR3 · R-3m (166) — Strukturbericht/word 'C19' in the TDB name
Candidate (tdb_comment): alpha-Sm · hR3 · R-3m — SmH-02Zin.tdb: 'Prototype alpha-Sm (hR3, R-3m)'
Stability: stable in 1 of 1 calculated diagram(s): 300–1006.98 K, x(H) 0–0.08519
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:rhomb-c19
paper: paper:10.1016/s0925-8388(01)01990-9:(α-Sm)
tdb: tdb:SmH-02Zin.tdb:RHOMB_C19

TDB models of RHOMB_C19 (1): PHASE and CONSTITUENT statements as written

SmH-02Zin.tdb: RHOMB_C19, type code %, sha256 3daabda9c80bc264…

55: PHASE RHOMB_C19 % 2 1 1 !
56: CONST RHOMB_C19 : SM : H VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase

SMH2_C1 (H–Sm)

Id: phase:h-sm:smh2-c1; status assigned
Structure: CaF2 · C1 · cF12 · Fm-3m (225); type st:c1-caf2-cf12; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1493.46 K, x(H) 0.62188–0.71672
Literature: 7 values (7 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:h-sm:smh2-c1
paper: paper:10.1016/s0925-8388(01)01990-9:SmH2-x, paper:10.1016/s0925-8388(01)01990-9:SmH2±x
tdb: tdb:SmH-02Zin.tdb:SMH2_C1

TDB models of SMH2_C1 (1): PHASE and CONSTITUENT statements as written

SmH-02Zin.tdb: SMH2_C1, type code %, sha256 3daabda9c80bc264…

60: PHASE SMH2_C1 % 3 1 2 1 !
61: CONST SMH2_C1 : SM : H VA : H VA : !

Example references (3 of 3; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(74)90025-3 M.H. Mintz, Z. Hadari, M. Bixon, Phase transformations in some rare earth-hydrogen systems, Journal of the Less Common Metals 37, 331-335 (1974).
cited as the source of values for this phase
doi:10.1016/0022-5088(76)90006-0 M.H. Mintz, D. Hiershler, Z. Hadari, Systematic study of the h.c.p. ⇌ f.c.c. transitions in the heavier LnH2-LnH3 systems, Journal of the Less Common Metals 48, 241-249 (1976).
cited as the source of values for this phase

SMH3 (H–Sm)

Id: phase:h-sm:smh3; status assigned
Structure: HoH3 · hP24 · P-3c1 (165); type st:hoh3-hp24; 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_structure_token, off_stoichiometric_model); structure as stated in the SGTE crystallographic table for this phase name and system
Stability: stable in 1 of 1 calculated diagram(s): 300–580.77 K, x(H) 0.73094–0.74986
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:h-sm:smh3
paper: paper:10.1016/s0925-8388(01)01990-9:SmH3-y
tdb: tdb:SmH-02Zin.tdb:SMH3

TDB models of SMH3 (1): PHASE and CONSTITUENT statements as written

SmH-02Zin.tdb: SMH3, type code %, sha256 3daabda9c80bc264…

65: PHASE SMH3 % 3 1 2 1 !
66: CONST SMH3 : SM : H : H VA : !

Example references (3 of 3; assessments first):

doi:10.1016/S0925-8388(01)01990-9 M. Zinkevich, N. Mattern, A. Handstein, O. Gutfleisch, J. Alloys Compd., 339, 118-139(2002).
assessment that models this phase; reports values for this phase
doi:10.1016/0022-5088(74)90025-3 M.H. Mintz, Z. Hadari, M. Bixon, Phase transformations in some rare earth-hydrogen systems, Journal of the Less Common Metals 37, 331-335 (1974).
cited as the source of values for this phase
doi:10.1016/0022-5088(76)90006-0 M.H. Mintz, D. Hiershler, Z. Hadari, Systematic study of the h.c.p. ⇌ f.c.c. transitions in the heavier LnH2-LnH3 systems, Journal of the Less Common Metals 48, 241-249 (1976).
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}
}