Gd–H phases

5 phases (tier A 1, liquid 1, gas 1, needs_review 1, interstitial_fcc_a1_compound 1); 5 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 · Gd–H system page · Markdown · field reference

Phases of the Gd–H system (5)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:gd-h:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1221.91–1586.6 K, x(H) 0–0.00033	0	1
FCC_A1 phase:gd-h:fcc-a1	CaF2 · C1 · cF12 · Fm-3m (225)	assigned	stable in 1 of 1 calculated diagram(s): 300–1468.03 K, x(H) 0.52934–0.70081	0	1
GAS phase:gd-h:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–2500 K, x(H) 1–1	2	1
HCP_A3 phase:gd-h:hcp-a3		needs_review	stable in 1 of 1 calculated diagram(s): 300–1916.51 K, x(H) 0–0.75	1	1
LIQUID phase:gd-h:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1586.6–2500 K, x(H) 0–0.00509	0	1

BCC_A2 (Gd–H)

Id: phase:gd-h: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): 1221.91–1586.6 K, x(H) 0–0.00033
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:gd-h:bcc-a2
tdb: tdb:GdH-16Fu.tdb:BCC_A2

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

GdH-16Fu.tdb: BCC_A2, type code %B, sha256 aaac49e5806f315d…

41: PHASE BCC_A2 %B 2 1 1 !
42: CONST BCC_A2 : GD : H VA% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.02.201 Kai Fu, Guoling Li, Jigang Li, Yang Liu, Wenhuai Tian, Jie Zheng et al., Study on the thermodynamics of the gadolinium-hydrogen binary system (H/Gd = 0.0–2.0) and implications to metallic gadolinium purification, Journal of Alloys and Compounds 673, 131-137 (2016).
assessment that models this phase

FCC_A1 (Gd–H)

Id: phase:gd-h:fcc-a1; status assigned
Structure: CaF2 · C1 · cF12 · Fm-3m (225); type st:c1-caf2-cf12; interstitial_fcc_a1_compound; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1468.03 K, x(H) 0.52934–0.70081
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:gd-h:fcc-a1
tdb: tdb:GdH-16Fu.tdb:FCC_A1

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

GdH-16Fu.tdb: FCC_A1, type code %A, sha256 aaac49e5806f315d…

36: PHASE FCC_A1 %A 3 1 1 2 !
37: CONST FCC_A1 : GD : H VA : H VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.02.201 Kai Fu, Guoling Li, Jigang Li, Yang Liu, Wenhuai Tian, Jie Zheng et al., Study on the thermodynamics of the gadolinium-hydrogen binary system (H/Gd = 0.0–2.0) and implications to metallic gadolinium purification, Journal of Alloys and Compounds 673, 131-137 (2016).
assessment that models this phase

GAS (Gd–H)

Id: phase:gd-h:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–2500 K, x(H) 1–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:gd-h:gas
paper: paper:10.1016/j.jallcom.2016.02.201:Gas(H2)
tdb: tdb:GdH-16Fu.tdb:GAS

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

GdH-16Fu.tdb: GAS, type code %, sha256 aaac49e5806f315d…

50: PHASE GAS:G % 1 1 !
51: CONST GAS:G : H H2 : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.02.201 Kai Fu, Guoling Li, Jigang Li, Yang Liu, Wenhuai Tian, Jie Zheng et al., Study on the thermodynamics of the gadolinium-hydrogen binary system (H/Gd = 0.0–2.0) and implications to metallic gadolinium purification, Journal of Alloys and Compounds 673, 131-137 (2016).
assessment that models this phase; reports values for this phase

HCP_A3 (Gd–H)

Id: phase:gd-h:hcp-a3; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:sgte_mmc2_row_disagrees_with_name; sgte_mmc2_row_disagrees_with_name:HCP_A3
Candidate (dft_mp): Fm-3m (225) — on-hull MP GdH2 at x(H)=0.6667
Candidate (dft_mp): P-3c1 (165) — on-hull MP GdH3 at x(H)=0.7500
Candidate (dft_oqmd): Fm-3m (225) — on-hull OQMD Gd1 H2 at x(H)=0.6667
Candidate (dft_oqmd): P-3c1 (165) — on-hull OQMD Gd1 H3 at x(H)=0.7500
Candidate (literature_printed): HoH3 · hP24 — printed with a label mapped to this phase
Candidate (name_token): Mg · A3 · hP2 · P6_3/mmc (194) — Strukturbericht/word 'A3' in the TDB name
Candidate (sgte_mmc2): HoH3 · hP24 · P-3c1 (165) — Hallstedt 2025 mmc2 row for HCP_A3: DyH3, ErH3, GdH3, YH3
Stability: stable in 1 of 1 calculated diagram(s): 300–1916.51 K, x(H) 0–0.75
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:gd-h:hcp-a3
paper: paper:10.1016/j.jallcom.2016.02.201:Hcp(Gd)
tdb: tdb:GdH-16Fu.tdb:HCP_A3

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

GdH-16Fu.tdb: HCP_A3, type code %A, sha256 aaac49e5806f315d…

47: PHASE HCP_A3 %A 3 1 1 2 !
48: CONST HCP_A3 : GD : H VA : H VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.02.201 Kai Fu, Guoling Li, Jigang Li, Yang Liu, Wenhuai Tian, Jie Zheng et al., Study on the thermodynamics of the gadolinium-hydrogen binary system (H/Gd = 0.0–2.0) and implications to metallic gadolinium purification, Journal of Alloys and Compounds 673, 131-137 (2016).
assessment that models this phase; reports values for this phase

LIQUID (Gd–H)

Id: phase:gd-h:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1586.6–2500 K, x(H) 0–0.00509
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:gd-h:liquid
tdb: tdb:GdH-16Fu.tdb:LIQUID

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

GdH-16Fu.tdb: LIQUID, type code %, sha256 aaac49e5806f315d…

31: PHASE LIQUID:L % 1 1 !
32: CONST LIQUID:L : GD H : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.02.201 Kai Fu, Guoling Li, Jigang Li, Yang Liu, Wenhuai Tian, Jie Zheng et al., Study on the thermodynamics of the gadolinium-hydrogen binary system (H/Gd = 0.0–2.0) and implications to metallic gadolinium purification, Journal of Alloys and Compounds 673, 131-137 (2016).
assessment that models 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}
}