Ta system

51 accepted literature values from 10 paper(s) (experimental 10, model 3, DFT 33, unspecified 5); 0 calculated phase diagram(s).

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Accepted values by evidence class
Evidence class	Values
experimental	10
model	3
DFT	33
unspecified	5

Accepted values by property group
Property group	Values
formation	15
activity / EMF / Gibbs energy	2
crystal structure	28
other property	6

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, Ta system (15)
Phase	Value	T (K)	Class	Source	Location
A15	3.0195 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 2, p. 22, row 4 report
C14	9.35 kJ/mol (basis unstated)	0	DFT	[2] Pavlů 2009	Table 3, p. 3, row 5 report
C14	9.6703 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 2, p. 22, row 12 report
C14	9.7 kJ/mol (basis unstated)	0	DFT	[2] Pavlů 2009 cites Sluiter 2006 doi	Table 3, p. 3, row 6 report
C15	10.94 kJ/mol (basis unstated)	0	DFT	[2] Pavlů 2009	Table 3, p. 3, row 11 report
C15	11.1655 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 2, p. 22, row 16 report
C15	11.2 kJ/mol (basis unstated)	0	DFT	[2] Pavlů 2009 cites Sluiter 2006 doi	Table 3, p. 3, row 12 report
C16	48.1965 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 2, p. 22, row 20 report
C36	10.15 kJ/mol (basis unstated)	0	DFT	[2] Pavlů 2009	Table 3, p. 3, row 15 report
FCC	23.3493 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 3, p. 27, row 10 report
HCP	26.9804 kJ/mol (basis unstated)	0	DFT	[1] Wang 2019	Table 3, p. 27, row 15 report
Ta	0 kJ/mol (basis unstated)	298.15	experimental	[3] Witusiewicz 2011	Table 4, p. 10, row 8 report
Ta	0 kJ/mol-atom		DFT	[4] Zhou 2009	Table 6, p. 7, row 6 report
Ta	26.23 kJ/mol-atom		DFT	[4] Zhou 2009	Table 6, p. 7, row 5 report
Ta13	10.71 kJ/mol-atom	0	DFT	[5] Rajkumar 2015	Table 9, p. 6, row 8 report

Other properties

Activity / EMF / Gibbs energy (2)

Activity / EMF / Gibbs energy, Ta system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Gibbs energy printed: Gm(ω)-Gm(β)	7795 J/mol	0	UNKNOWN alloy: Ta 1	model	[6] Yan 2016	Table 4, p. 5, row 6 report
Gibbs energy printed: Gm(ω)-Gm(β)	21835 J/mol	0	UNKNOWN alloy: Ta 1	DFT	[6] Yan 2016	Table 4, p. 5, row 5 report

Crystal structure (28)

Crystal structure, Ta system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Lattice a	5.45 Å	0	C14 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 3 report
Lattice a	7.65 Å	0	C15 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 12 report
Lattice a	5.44 Å	0	C36 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 21 report
Lattice a	3.31 Å		Nonmagnetic BCC Ta alloy: Ta 1	unspecified	[2] Pavlů 2009	Table 1, p. 3, row 5 report
Lattice a	3.303 Å	298.15	(Ta) alloy: Ta 1	model	[7] Broz 2013 cites Smith 1983 doi	Table 1, p. 3, row 1 report
Lattice a	3.3 Å	298.15	Nonmagnetic BCC Ta alloy: Ta 1	experimental	[2] Pavlů 2009 cites Villars 1991	Table 1, p. 3, row 6 report
Lattice a	3.328 Å	298.15	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 1, p. 12, row 2 report
Lattice a	3.316 Å	298.15	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 1, p. 12, row 1 report
Lattice a	3.32 Å	298.15	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017 cites ref. 36	Table 1, p. 12, row 5 report
Lattice a	3.33 Å	298.15	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 1, p. 12, row 3 report
Lattice a	3.3 Å	298.15	bcc-Ta alloy: Ta 1	experimental	[8] Marker 2017 cites ref. 35	Table 1, p. 12, row 4 report
Lattice a	3.3065 Å	298.15	β, (Ta) alloy: Ta 1	model	[3] Witusiewicz 2011 cites Massalski 1990	Table 1, p. 2, row 3 report
Lattice a	3.303 Å	298.15	β, (Ta), bcc_A2 alloy: Ta 1	experimental	[9] Witusiewicz 2010 cites 3 vols 1990	Table 1, p. 2, row 3 report
Lattice a	3.303 Å	300	(Ta) alloy: Ta 1	experimental	[7] Broz 2013 cites Smith 1983 doi	Table 1, p. 3, row 48 report
Lattice c	8.68 Å	0	C14 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 3 report
Lattice c	17.43 Å	0	C36 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 21 report
Molar volume printed: V	18.241 Å³/atom	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 2, p. 13, row 1 report
Molar volume printed: V	18.313 Å³/atom	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017 cites ref. 36	Table 2, p. 13, row 3 report
Molar volume printed: V	17.9685 Å³/atom		bcc-Ta alloy: Ta 1	experimental	[8] Marker 2017 cites ref. 35	Table 2, p. 13, row 2 report
lattice 2v atom	3.724 10^7 pm^3	0	C36 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 21 report
lattice unspecified axis printed: Lattice constant	3.3031 Å		Pure Ta alloy: Ta 1	experimental	[10] Turchi 2005	Table I, p. 5, row 1 report
lattice unspecified axis printed: Lattice constant	3.2766 Å		Pure Ta alloy: Ta 1	unspecified	[10] Turchi 2005	Table I, p. 5, row 8 report
lattice unspecified axis printed: Lattice constant	3.3098 Å		Pure Ta alloy: Ta 1	unspecified	[10] Turchi 2005	Table I, p. 5, row 4 report
lattice v atom	1.861 10^7 pm^3	0	C14 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 3 report
lattice v atom	1.862 10^7 pm^3	0	C15 alloy: Ta 1	DFT	[2] Pavlů 2009	Table 2, p. 3, row 12 report
volume printed: V	18.241 Å3/atom	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 2, p. 13, row 1 report
volume printed: V	18.313 Å3/atom	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017 cites ref. 36	Table 2, p. 13, row 3 report
volume printed: V	17.9685 Å3/atom		bcc-Ta alloy: Ta 1	experimental	[8] Marker 2017 cites ref. 35	Table 2, p. 13, row 2 report

Other property (6)

Other property, Ta system
Property	Value	T (K)	Phases / composition	Class	Source	Location
bulk modulus printed: Bulk modulus	196.1 GPa		Pure Ta alloy: Ta 1	experimental	[10] Turchi 2005	Table I, p. 5, row 1 report
bulk modulus printed: Bulk modulus	206.4 GPa		Pure Ta alloy: Ta 1	unspecified	[10] Turchi 2005	Table I, p. 5, row 4 report
bulk modulus printed: Bulk modulus	215.3 GPa		Pure Ta alloy: Ta 1	unspecified	[10] Turchi 2005	Table I, p. 5, row 8 report
bulk modulus printed: B	193.7 GPa	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017	Table 2, p. 13, row 1 report
bulk modulus printed: B	195.3 GPa	0	bcc-Ta alloy: Ta 1	DFT	[8] Marker 2017 cites ref. 36	Table 2, p. 13, row 3 report
bulk modulus printed: B	200 GPa		bcc-Ta alloy: Ta 1	experimental	[8] Marker 2017 cites ref. 35	Table 2, p. 13, row 2 report

Sources

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

Peisheng Wang, Jörg Koßmann, Ursula R. Kattner, Mauro Palumbo, Thomas Hammerschmidt, Gregory B. Olson, Thermodynamic assessment of the Co-Ta system, Calphad 64, 205-212 (2019). doi:10.1016/j.calphad.2018.12.002
J. Pavlů, J. Vřešt’ál, M. Šob, Re-modeling of Laves phases in the Cr–Nb and Cr–Ta systems using first-principles results, Calphad 33, 179-186 (2009). doi:10.1016/j.calphad.2008.04.006
V.T. Witusiewicz, A.A. Bondar, U. Hecht, V.M. Voblikov, O.S. Fomichov, V.M. Petyukh et al., Experimental study and thermodynamic re-assessment of the binary Fe–Ta system, Intermetallics 19, 1059-1075 (2011). doi:10.1016/j.intermet.2011.03.018
S.H. Zhou, Y. Wang, L.-Q. Chen, Z.-K. Liu, R.E. Napolitano, Solution-based thermodynamic modeling of the Ni–Ta and Ni–Mo–Ta systems using first-principle calculations, Calphad 33, 631-641 (2009). doi:10.1016/j.calphad.2009.06.006
V.B. Rajkumar, K.C. Hari Kumar, Gibbs energy modeling of Fe–Ta system by Calphad method assisted by experiments and ab initio calculations, Calphad 48, 157-165 (2015). doi:10.1016/j.calphad.2014.12.006
Jia-Yi Yan, G.B. Olson, Computational thermodynamics and kinetics of displacive transformations in titanium-based alloys, Journal of Alloys and Compounds 673, 441-454 (2016). doi:10.1016/j.jallcom.2016.02.251
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
Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017). doi:10.1016/j.calphad.2017.03.001
V.T. Witusiewicz, A.A. Bondar, U. Hecht, J. Zollinger, V.M. Petyukh, O.S. Fomichov et al., Experimental study and thermodynamic re-assessment of the binary Al–Ta system, Intermetallics 18, 92-106 (2010). doi:10.1016/j.intermet.2009.06.015
P. E. A. Turchi, V. Drchal, J. Kudrnovský, C. Colinet, Larry Kaufman, Zi-Kui Liu, Application of<i>ab initio</i>and CALPHAD thermodynamics to Mo-Ta-W alloys, Phys. Rev. B 71 (2005). doi:10.1103/physrevb.71.094206

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 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); 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; 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). 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_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}
}