H–Ni system

28 accepted literature values from 2 paper(s) (experimental 22, model 6); 0 calculated phase diagram(s). 1 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: JSON · CSV · interactive explorer · phases (5) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	22
model	6

Accepted values by property group
Property group	Values
invariant reaction	6
phase transition	2
formation	2
mixing / partial	18

Convex hulls: Materials Project DFT hull · OQMD DFT hull · CALPHAD hull NiH-99Zen

Invariant reactions (literature)

Invariant reactions reported in the literature for the H–Ni system (6)
T (K)	Reaction / phases	Compositions (mole fraction)	Class	Source	Location
1706.15	(Ni)+gas->L	(Ni): H 0.009; L: H 0.024	model	[1] Zeng 1999	Table 5, p. 9, row 2 report
1705.15	(Ni)+gas->L	L: H 0.021	experimental	[1] Zeng 1999 cites Shapovalov 1979	Table 5, p. 9, row 1 report
1679.15	(Ni)+gas->L	(Ni): H 0.011; L: H 0.036	experimental	[1] Zeng 1999 cites Shapovalov	Table 5, p. 9, row 3 report
1679.15	(Ni)+gas->L	(Ni): H 0.018; L: H 0.053	model	[1] Zeng 1999	Table 5, p. 9, row 4 report
1678.15	(Ni)+gas->L	(Ni): H 0.016	experimental	[1] Zeng 1999 cites Serdyuk 1992	Table 5, p. 9, row 5 report
1659.15	(Ni)+gas->L	(Ni): H 0.025; L: H 0.075	model	[1] Zeng 1999	Table 5, p. 9, row 6 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, H–Ni system (2)
Phase	Compound	Value	T (K)	Class	MP DFT (kJ/mol-atom)	OQMD DFT (kJ/mol-atom)	Source	Location	Quote
(Ce)(Ni)5(H)7		-19.257 kJ/mol (basis unstated)		model			[2] Hannappel 2024	Table 3, p. 5, row 3 report
(Ce)(Ni)5(H)7		-11.176 kJ/mol (basis unstated)		model			[2] Hannappel 2024	Table 3, p. 5, row 3 report

Other properties

Phase transition (2)

Phase transition, H–Ni system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Phase transition	1726.15 K	1726.15	other	model	[1] Zeng 1999	p. 10 report	At 1 bar, the experimental value is 14558C [21], while the calculated is 14538C (see Fig. 1).
Phase transition	1728.15 K	1728.15	other	experimental	[1] Zeng 1999 cites Shapovalov 1979	p. 10 report	At 1 bar, the experimental value is 14558C [21], while the calculated is 14538C (see Fig. 1).

Mixing / partial (18)

Mixing / partial, H–Ni system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Partial enthalpy printed: ΔH of solution	8.4 kJ/mol-atom	182.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 12 report
Partial enthalpy printed: ΔH of solution	16.93 kJ/mol-atom	264	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 17 report
Partial enthalpy printed: ΔH of solution	14.25 kJ/mol-atom	323.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 15 report
Partial enthalpy printed: ΔH of solution	10.96 kJ/mol-atom	327.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 1 report
Partial enthalpy printed: ΔH of solution	8.03 kJ/mol-atom	388.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 16 report
Partial enthalpy printed: ΔH of solution	12.72 kJ/mol-atom	406	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 5 report
Partial enthalpy printed: ΔH of solution	11.76 kJ/mol-atom	450	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 14 report
Partial enthalpy printed: ΔH of solution	12.7 kJ/mol-atom	500	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 3 report
Partial enthalpy printed: ΔH of solution	12.09 kJ/mol-atom	502.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 13 report
Partial enthalpy printed: ΔH of solution	12.34 kJ/mol-atom	600	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 2 report
Partial enthalpy printed: ΔH of solution	10.64 kJ/mol-atom	666.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 18 report
Partial enthalpy printed: ΔH of solution	12.24 kJ/mol-atom	725	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 11 report
Partial enthalpy printed: ΔH of solution	10.8 kJ/mol-atom	727	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 6 report
Partial enthalpy printed: ΔH of solution	15.2 kJ/mol-atom	750	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 8 report
Partial enthalpy printed: ΔH of solution	13.6 kJ/mol-atom	806	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 7 report
Partial enthalpy printed: ΔH of solution	15.1 kJ/mol-atom	945	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 9 report
Partial enthalpy printed: ΔH of solution	15.7 kJ/mol-atom	977.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 4 report
Partial enthalpy printed: ΔH of solution	16.65 kJ/mol-atom	984.5	UNKNOWN	experimental	[1] Zeng 1999	Table 3, p. 3, row 10 report

Sources

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

Kejun Zeng, T. Klassen, W. Oelerich, R. Bormann, Thermodynamics of the Ni–H system, Journal of Alloys and Compounds 283, 151-161 (1999). doi:10.1016/s0925-8388(98)00857-3
Peter Hannappel, Ebert Alvares, Felix Heubner, Claudio Pistidda, Paul Jerabek, Thomas Weißgärber, Thermodynamic assessment of the Ce H and CeNi5 H system, Calphad 85, 102701 (2024). doi:10.1016/j.calphad.2024.102701

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-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); 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); 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. 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_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}
}