NiTi2: enthalpy of formation

13 accepted literature formation-enthalpy value(s) (experimental 3, model 8, DFT 2); experimental median -26.8 kJ/mol-atom (n = 1); Materials Project -26.758 kJ/mol-atom (mp-aaaaacro); OQMD -33.202 kJ/mol-atom (oqmd-1372059).

Systems: Ni–Ti

Literature values

Enthalpy of formation of NiTi2 reported in the literature (13)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-29.3 per mol-atom ± 500	NiTi2	1202.15	experimental		Ni–Ti	[1] Santhy 2015 cites Gachon 1981 doi	Table 9, p. 6, row 31 report
-26.896 per mol-atom ± 2000	NiTi2	298.15	experimental		Ni–Ti	[1] Santhy 2015 cites Kubaschewski 1956 doi	Table 9, p. 6, row 29 report
-26.8 kJ/mol-atom	Ti2Ni	298.15	experimental	Direct synthesis calorimetry	Ni–Ti	[2] Povoden-Karadeniz 2013 cites Kubaschewski 1958 doi	Table 6, p. 8, row 16 report
-35.3 per mol-atom	NiTi2	298.15	model	Miedema	Ni–Ti	[1] Santhy 2015	Table 9, p. 6, row 36 report
-33.7 per mol-atom	NiTi2		model	FP	Ni–Ti	[1] Santhy 2015 cites Pasturel 1995 doi	Table 9, p. 6, row 33 report
-30.393 per mol-atom	NiTi2	1202.15	model		Ni–Ti	[1] Santhy 2015	Table 9, p. 6, row 32 report
-28.96 per mol-atom	NiTi2		model	FP	Ni–Ti	[1] Santhy 2015	Table 9, p. 6, row 35 report
-28.2 per mol-atom	NiTi2		model	FP	Ni–Ti	[1] Santhy 2015 cites Pasturel 1995 doi	Table 9, p. 6, row 34 report
-26.977 kJ/mol-atom	Ti2Ni	298.15	model	Calphad assessment	Ni–Ti	[2] Povoden-Karadeniz 2013	Table 6, p. 8, row 14 report
-26.901 kJ/mol-atom	Ti2Ni	298.15	model	Calphad assessment	Ni–Ti	[2] Povoden-Karadeniz 2013 cites Bellen 1996	Table 6, p. 8, row 15 report
-25.849 per mol-atom	NiTi2	298.15	model		Ni–Ti	[1] Santhy 2015	Table 9, p. 6, row 30 report
-33.7 kJ/mol-atom	Ti2Ni	0	DFT	1st-princ. (LMTO-ASA)	Ni–Ti	[2] Povoden-Karadeniz 2013 cites Pasturel 1995 doi	Table 6, p. 8, row 19 report
-28.2 kJ/mol-atom	Ti2Ni	0	DFT	1st-princ. (FP-LMTO)	Ni–Ti	[2] Povoden-Karadeniz 2013 cites Pasturel 1995 doi	Table 6, p. 8, row 20 report

Uncertainty budget

Components kept separate, in the value's unit (literature SCHEMA.md, UNCERTAINTY_CALIBRATION.md): effective = max(sqrt(max(printed, reading, method)^2 + composition^2 + conversion^2), scatter). The method floor is the robust between-study scatter of the method class in ORCHID (calibrated) or a documented prior; printed values and printed uncertainties are unchanged.

Uncertainty budget of the literature values of NiTi2
Value	Unit	Printed	Reading	Method (class, basis)	Effective
-29.3	per mol-atom	500	5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	500
-26.896	per mol-atom	2000	5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	2000
-26.8	kJ/mol-atom		5.000e-4	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-35.3	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-33.7	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-30.393	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-28.96	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-28.2	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-26.977	kJ/mol-atom		5.000e-4	3.9 (model_calculated, calibrated)	3.9
-26.901	kJ/mol-atom		5.000e-4	3.9 (model_calculated, calibrated)	3.9
-25.849	per mol-atom		5.000e-4	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-33.7	kJ/mol-atom		5.000e-4	3.929 (dft, calibrated)	3.929
-28.2	kJ/mol-atom		5.000e-4	3.929 (dft, calibrated)	3.929

DFT formation energies

Lowest-energy entries at this composition. Materials Project and OQMD use different energy references and are never averaged. 1 eV/atom = 96.485 kJ/mol-atom.

DFT formation energy of NiTi2
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaacro	-26.758	-0.277329	Fd-3m	0	0	no
OQMD	oqmd-1372059	-33.202	-0.344118	I4/mmm	0	0	yes

DFT sources: A. Jain et al., Commentary: The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002. doi:10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501-1509; S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010. doi:10.1007/s11837-013-0755-4 (CC BY 4.0);

Sources

K. Santhy, K.C. Hari Kumar, Thermodynamic reassessment of Nb-Ni-Ti system with order–disorder model, Journal of Alloys and Compounds 619, 733-747 (2015). doi:10.1016/j.jallcom.2014.08.200
E. Povoden-Karadeniz, D.C. Cirstea, P. Lang, T. Wojcik, E. Kozeschnik, Thermodynamics of Ti–Ni shape memory alloys, Calphad 41, 128-139 (2013). doi:10.1016/j.calphad.2013.02.004

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-Parity: DFT-vs-experiment formation-enthalpy benchmark (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735943
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); G. Kim, S. V. Meschel, P. Nash, W. Chen, Experimental formation enthalpies for intermetallic phases and other inorganic compounds, Scientific Data 4 (2017) 170162, https://doi.org/10.1038/sdata.2017.162; 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_dft_benchmark_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735943},
  url       = {https://doi.org/10.5281/zenodo.23735943},
  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}
}