TaB2: enthalpy of formation

5 accepted literature formation-enthalpy value(s) (experimental 3, DFT 2); experimental median -62.9 kJ/mol-atom (n = 3); Materials Project -62.64 kJ/mol-atom (mp-aaaaabqq); OQMD -62.619 kJ/mol-atom (oqmd-5807).

Systems: B–Ta

Literature values

Enthalpy of formation of TaB2 reported in the literature (5)
Value	Phase as printed	T (K)	Class	System	Source	Location
-64.9 kJ/mol-atom	TaB2	298.15	experimental	B–Ta	[1] OuYang 2017 cites Kirpichev 1979	Table 1, p. 4, row 17 report
-62.9 kJ/mol-atom	TaB2	298.15	experimental	B–Ta	[1] OuYang 2017 cites Johnson 1967 doi	Table 1, p. 4, row 18 report
-53.3 kJ/mol-atom	TaB2	298.15	experimental	B–Ta	[1] OuYang 2017 cites Meschel 1993 doi	Table 1, p. 4, row 19 report
-67.7 kJ/mol-atom	TaB2	0	DFT	B–Ta	[1] OuYang 2017 cites Zhang 2015 doi	Table 1, p. 4, row 16 report
-64.062 kJ/mol-atom	TaB2	0	DFT	B–Ta	[1] OuYang 2017	Table 1, p. 4, row 14 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 TaB2
Value	Unit	Reading	Method (class, basis)	Effective
-64.9	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-62.9	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-53.3	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-67.7	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-64.062	kJ/mol-atom	5.000e-4	9.966 (dft, calibrated)	9.966

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 TaB2
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaabqq	-62.64	-0.649217	P6/mmm	0	0	no
OQMD	oqmd-5807	-62.619	-0.649001	P6/mmm	2.6053	0.027	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

Xuemei OuYang, Fucheng Yin, Jingxian Hu, Ye Liu, Zhaohui Long, Thermodynamic Modeling of B-Ta and B-C-Ta Systems, J. Phase Equilib. Diffus. 38, 874-886 (2017). doi:10.1007/s11669-017-0603-2

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}
}