Si3Ta5: enthalpy of formation

23 accepted literature formation-enthalpy value(s) (experimental 11, model 8, DFT 1, unspecified 3); experimental median -39.7 kJ/mol-atom (n = 11); Materials Project -57.039 kJ/mol-atom (mp-aaaaacyn); OQMD -59.481 kJ/mol-atom (oqmd-3573).

Systems: Si–Ta

Literature values

Enthalpy of formation of Si3Ta5 reported in the literature (23)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-54.937 kJ/mol-atom	Si0.375Ta0.625_HT	1027	experimental	Method unknown	Si–Ta	[1] Drouelle 2013 cites Levine 1969 doi	Table 2, p. 2, row 19 report
-52.423 kJ/mol-atom	Si0.375Ta0.625_HT	1900	experimental	Kundsen eff. method	Si–Ta	[1] Drouelle 2013 cites Myers 1957 doi	Table 2, p. 2, row 17 report
-41.9 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	experimental	Kundsen eff. method	Si–Ta	[1] Drouelle 2013 cites Myers 1957 doi	Table 2, p. 2, row 15 report
-41.8 kJ/mol-atom ± 7.8	Ta5Si3 (α)	298.15	experimental		Si–Ta	[2] Broz 2013 cites Myers 1957	Table 2, p. 6, row 50 report
-39.7 kJ/mol-atom	Ta5Si3 (α)	298.15	experimental		Si–Ta	[2] Broz 2013 cites Robins 1955 doi	Table 2, p. 6, row 53 report
-39.7 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	experimental	Calorimetric method	Si–Ta	[1] Drouelle 2013 cites Robins 1955 doi	Table 2, p. 2, row 14 report
-38.1 kJ/mol-atom ± 1.7	Si0.375Ta0.625_HT	1473	experimental	DSC	Si–Ta	[1] Drouelle 2013 cites Meschel 1998 doi	Table 2, p. 2, row 12 report
-38.1 kJ/mol-atom ± 1.7	Ta5Si3 (α)	298.15	experimental		Si–Ta	[2] Broz 2013 cites Meschel 1998 doi	Table 2, p. 6, row 51 report
-38.1 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	experimental	HT calorimetry	Si–Ta	[1] Drouelle 2013 cites Nowotny 1956 doi	Table 2, p. 2, row 13 report
-37.7 kJ/mol-atom ± 4.7	Ta5Si3 (α)	298.15	experimental		Si–Ta	[2] Broz 2013 cites Levine 1969 doi	Table 2, p. 6, row 52 report
-37.7 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	experimental	EMF	Si–Ta	[1] Drouelle 2013 cites Levine 1969 doi	Table 2, p. 2, row 11 report
-56.2 kJ/mol-atom	Ta5Si3 (α)		model		Si–Ta	[2] Broz 2013 cites Tao 2011	Table 2, p. 6, row 54 report
-55 kJ/mol-atom	Si0.375Ta0.625_LT	298.15	model	Prediction	Si–Ta	[1] Drouelle 2013 cites F 1988	Table 2, p. 2, row 9 report
-52.42 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	model	Pred., Ab-in;	Si–Ta	[1] Drouelle 2013 cites Tao 2009 doi	Table 2, p. 2, row 18 report
-52.4 kJ/mol-atom	Ta5Si3 (β)		model		Si–Ta	[2] Broz 2013 cites Tao 2011	Table 2, p. 6, row 57 report
-52.3815 kJ/mol-atom	Si0.375Ta0.625_HT	298.15	model	Optimization	Si–Ta	[1] Drouelle 2013	Table 2, p. 2, row 16 report
-52.3807 kJ/mol-atom	Si0.375Ta0.625_LT	298.15	model	Optimization	Si–Ta	[1] Drouelle 2013	Table 2, p. 2, row 8 report
-52.3 kJ/mol-atom	Ta5Si3 (α)	0	model		Si–Ta	[2] Broz 2013 cites Guo 2009 doi	Table 2, p. 6, row 55 report
-51.6 kJ/mol-atom	Ta5Si3 (β)	0	model		Si–Ta	[2] Broz 2013 cites Guo 2009 doi	Table 2, p. 6, row 58 report
-56.15 kJ/mol-atom	Si0.375Ta0.625_LT	298.15	DFT	Ab-initio	Si–Ta	[1] Drouelle 2013 cites Tao 2009 doi	Table 2, p. 2, row 10 report
-59.8 kJ/mol-atom	Ta5Si3 (α)	0	unspecified		Si–Ta	[2] Broz 2013	Table 2, p. 6, row 49 report
-55.4 kJ/mol-atom	Ta5Si3 (β)	0	unspecified		Si–Ta	[2] Broz 2013	Table 2, p. 6, row 56 report
-48.1 kJ/mol-atom	Ta5Si3	0	unspecified		Si–Ta	[2] Broz 2013	Table 2, p. 6, row 59 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 Si3Ta5
Value	Unit	Printed	Reading	Method (class, basis)	Effective
-54.937	kJ/mol-atom		5.000e-4	4.1 (experimental_unspecified, cleaned_below_threshold)	4.1
-52.423	kJ/mol-atom		5.000e-5	4.2 (kems_vapour, calibrated)	4.2
-41.9	kJ/mol-atom		5.000e-5	4.2 (kems_vapour, calibrated)	4.2
-41.8	kJ/mol-atom	7.8	0.05	3.5 (unknown, calibrated)	7.8
-39.7	kJ/mol-atom		0.05	3.5 (unknown, calibrated)	3.5
-39.7	kJ/mol-atom		5.000e-5	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-38.1	kJ/mol-atom	1.7	5.000e-5	2 (dsc_dta, prior)	2
-38.1	kJ/mol-atom	1.7	0.05	3.5 (unknown, calibrated)	3.5
-38.1	kJ/mol-atom		5.000e-4	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-37.7	kJ/mol-atom	4.7	0.05	3.5 (unknown, calibrated)	4.7
-37.7	kJ/mol-atom		5.000e-4	4.6 (emf, cleaned_below_threshold)	4.6
-56.2	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-55	kJ/mol-atom		5.000e-5	3.9 (model_calculated, calibrated)	3.9
-52.42	kJ/mol-atom		5.000e-5	3.9 (model_calculated, calibrated)	3.9
-52.4	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-52.3815	kJ/mol-atom		5.000e-8	3.9 (model_calculated, calibrated)	3.9
-52.3807	kJ/mol-atom		5.000e-8	3.9 (model_calculated, calibrated)	3.9
-52.3	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-51.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-56.15	kJ/mol-atom		5.000e-5	9.966 (dft, calibrated)	9.966
-59.8	kJ/mol-atom		0.05	3.5 (unknown, calibrated)	3.5
-55.4	kJ/mol-atom		0.05	3.5 (unknown, calibrated)	3.5
-48.1	kJ/mol-atom		0.05	3.5 (unknown, calibrated)	3.5

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 Si3Ta5
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaacyn	-57.039	-0.591172	I4/mcm	0	0	no
OQMD	oqmd-3573	-59.481	-0.616476	I4/mcm	0	0	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

I. Drouelle, C. Servant, Thermodynamic assessment of the Si–Ta system, Journal of Alloys and Compounds 551, 293-299 (2013). doi:10.1016/j.jallcom.2012.09.148
P. Broz, A.U. Khan, H. Niu, X.-Q. Chen, D. Li, J. Vrestal et al., The system Ta–V–Si: Thermodynamic modeling, Journal of Solid State Chemistry 199, 171-180 (2013). doi:10.1016/j.jssc.2012.12.003

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}
}