Nb3Si: enthalpy of formation

11 accepted literature formation-enthalpy value(s) (model 9, DFT 2); Materials Project -40.615 kJ/mol-atom (mp-aaaabakm); OQMD -42.633 kJ/mol-atom (oqmd-2033).

Systems: Nb–Si

Literature values

Enthalpy of formation of Nb3Si reported in the literature (11)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-35.85 kJ/mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004 cites Fernandes 2002 doi	Table 3, p. 6, row 4 report
-33.75 per mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004 cites Fernandes 2002 doi	Table 3, p. 6, row 22 report
-33.357 kJ/mol (basis unstated)	Nb3Si	298.15	model	Calphad	Nb–Si	[2] Utton 2017	Table 2, p. 6, row 12 report
-33.163 kJ/mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004 cites Yang 2003 doi	Table 3, p. 6, row 1 report
-32 kJ/mol (basis unstated)	Nb3Si	298.15	model	Calphad	Nb–Si	[2] Utton 2017	Table 2, p. 6, row 16 report
-30.301 kJ/mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004 cites Liang 1999 doi	Table 3, p. 6, row 2 report
-29.6425 kJ/mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004	Table 3, p. 6, row 5 report
-28.175 kJ/mol-atom	Nb3Si	298.15	model		Nb–Si	[3] Liang 1999 cites Kaufman 1979 doi	Table 2, p. 4, row 9 report
-28.175 kJ/mol-atom	Nb3Si	298.15	model	CALPHAD	Nb–Si	[1] Shao 2004 cites Kaufman 1979 doi	Table 3, p. 6, row 3 report
-37.3 kJ/mol (basis unstated)	Nb3Si	0	DFT	ab initio	Nb–Si	[2] Utton 2017 cites Papadimitriou 2015 doi	Table 2, p. 6, row 11 report
-34.73 kJ/mol (basis unstated)	Nb3Si	0	DFT	ab initio	Nb–Si	[2] Utton 2017 cites Papadimitriou 2015 doi	Table 2, p. 6, row 15 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 Nb3Si
Value	Unit	Reading	Method (class, basis)	Effective
-35.85	kJ/mol-atom	0.005	3.9 (model_calculated, calibrated)	3.9
-33.75	per mol-atom	0.005	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-33.357	kJ/mol (basis unstated)	5.000e-4	15.6 (model_calculated, calibrated)	15.6
-33.163	kJ/mol-atom	5.000e-4	3.9 (model_calculated, calibrated)	3.9
-32	kJ/mol (basis unstated)	0.5	15.6 (model_calculated, calibrated)	15.6
-30.301	kJ/mol-atom	5.000e-4	3.9 (model_calculated, calibrated)	3.9
-29.6425	kJ/mol-atom	5.000e-5	3.9 (model_calculated, calibrated)	3.9
-28.175	kJ/mol-atom	5.000e-4	3.9 (model_calculated, calibrated)	3.9
-28.175	kJ/mol-atom	5.000e-4	3.9 (model_calculated, calibrated)	3.9
-37.3	kJ/mol (basis unstated)	0.05	39.86 (dft, calibrated)	39.86
-34.73	kJ/mol (basis unstated)	0.005	39.86 (dft, calibrated)	39.86

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 Nb3Si
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaabakm	-40.615	-0.420949	P4_2/n	1.3618	0.0141	no
OQMD	oqmd-2033	-42.633	-0.441856	P42/n	1.0964	0.0114	no

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

G. Shao, Thermodynamic assessment of the Nb–Si–Al system, Intermetallics 12, 655-664 (2004). doi:10.1016/j.intermet.2004.03.011
Claire A. Utton, Ioannis Papadimitriou, Hajime Kinoshita, Panos Tsakiropoulos, Experimental and thermodynamic assessment of the Ge-Nb-Si ternary phase diagram, Journal of Alloys and Compounds 717, 303-316 (2017). doi:10.1016/j.jallcom.2017.04.279
H. Liang, Y.A. Chang, Thermodynamic modeling of the Nb–Si–Ti ternary system, Intermetallics 7, 561-570 (1999). doi:10.1016/s0966-9795(98)00073-9

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}
}