Mg2Si: enthalpy of formation

32 accepted literature formation-enthalpy value(s) (experimental 18, model 7, DFT 5, unspecified 2); experimental median -26.15 kJ/mol-atom (n = 18); Materials Project -12.42 kJ/mol-atom (mp-aaaaacap); OQMD -15.603 kJ/mol-atom (oqmd-17649).

Systems: Mg–Si

Literature values

Enthalpy of formation of Mg2Si reported in the literature (32)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-61.9 kJ/mol-atom	Mg2Si	298.15	experimental	Knusden cell	Mg–Si	[1] Yuan 2009 cites ref. 1966Cau	Table 3, p. 3, row 6 report
-29.7 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[1] Yuan 2009 cites ref. 1971Bla	Table 3, p. 3, row 8 report
-27.9 kJ/mol-atom	Mg2Si	298.15	experimental	Knudsen cell	Mg–Si	[1] Yuan 2009 cites ref. 1963Rya	Table 3, p. 3, row 3 report
-27.1 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[1] Yuan 2009 cites ref. 1967Ger	Table 3, p. 3, row 7 report
-26.67 kJ/mol-atom	Mg2Si	298.15	experimental	emf	Mg–Si	[2] Yan 2000 cites Lukashenko 1964	Table 2, p. 4, row 4 report
-26.4 kJ/mol-atom	Mg2Si	298.15	experimental	emf	Mg–Si	[1] Yuan 2009 cites ref. 1964Luk	Table 3, p. 3, row 4 report
-26.4 kJ/mol-atom	Mg2Si	298.15	experimental		Mg–Si	[3] Schick 2012 cites Caulfield 1962	Table 3, p. 7, row 2 report
-26.37 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[2] Yan 2000 cites Caulfield 1962	Table 2, p. 4, row 3 report
-26.3 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[2] Yan 2000 cites Kubaschewski 1949	Table 2, p. 4, row 1 report
-26 kJ/mol-atom	Mg2Si	298.15	experimental		Mg–Si	[3] Schick 2012 cites Kubaschewski 1949	Table 3, p. 7, row 1 report
-25.9 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[1] Yuan 2009 cites ref. 1949Kub	Table 3, p. 3, row 1 report
-22.99 kJ/mol-atom	Mg2Si	298.15	experimental	Vapor pressure	Mg–Si	[2] Yan 2000 cites Eldridge 1967	Table 2, p. 4, row 5 report
-22.2 kJ/mol-atom	Mg2Si	298.15	experimental	emf	Mg–Si	[1] Yuan 2009 cites ref. 1981Rao	Table 3, p. 3, row 9 report
-22.16 kJ/mol-atom	Mg2Si	298.15	experimental	emf	Mg–Si	[2] Yan 2000 cites Rao 1981	Table 2, p. 4, row 6 report
-21.1 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[2] Yan 2000 cites Feufel 1997 doi	Table 2, p. 4, row 7 report
-21.1 kJ/mol-atom	Mg2Si	298.15	experimental	Calorimetry	Mg–Si	[1] Yuan 2009 cites ref. 1997Feu	Table 3, p. 3, row 10 report
-14.21 kJ/mol-atom	Mg2Si	298.15	experimental	Vapor pressure	Mg–Si	[2] Yan 2000 cites Grjotheim 1962	Table 2, p. 4, row 2 report
-14.2 kJ/mol-atom	Mg2Si	298.15	experimental	VPTM	Mg–Si	[1] Yuan 2009 cites ref. 1962Grj	Table 3, p. 3, row 2 report
-29.7 kJ/mol-atom	Mg2Si	298.15	model		Mg–Si	[3] Schick 2012 cites Blachnik 1971	Table 3, p. 7, row 3 report
-29.7 kJ/mol-atom	Mg2Si	298.15	model	Calculation	Mg–Si	[2] Yan 2000 cites Chakraborti 1992 doi	Table 2, p. 4, row 8 report
-26.47 kJ/mol-atom	Mg2Si	298.15	model	Calculation	Mg–Si	[2] Yan 2000 cites Ludecke 1986	Table 2, p. 4, row 9 report
-21.74 kJ/mol-atom	Mg2Si	298.15	model	Calculation	Mg–Si	[2] Yan 2000 cites Feufel 1997 doi	Table 2, p. 4, row 11 report
-21.37 kJ/mol-atom	Mg2Si	298.15	model	Calculation	Mg–Si	[2] Yan 2000	Table 2, p. 4, row 12 report
-21.01 kJ/mol-atom	Mg2Si	298.15	model	Calculation	Mg–Si	[2] Yan 2000 cites Lukas 1994	Table 2, p. 4, row 10 report
-21 kJ/mol-atom	Mg2Si		model	CALPHAD method	Mg–Si	[1] Yuan 2009	Table 3, p. 3, row 13 report
-18.2 kJ/mol-atom	Mg2Si	0	DFT	First-principles	Mg–Si	[1] Yuan 2009	Table 3, p. 3, row 12 report
-17.7 kJ/mol-atom	Mg2Si		DFT	First-principles	Mg–Si	[1] Yuan 2009 cites ref. 2009Zha	Table 3, p. 3, row 11 report
-17.7 kJ/mol-atom	Mg2Si	298.15	DFT	ab initio	Mg–Si	[3] Schick 2012 cites Zhang 2009 doi	Table 3, p. 7, row 5 report
-16.7 kJ/mol-atom	Mg2Si	298.15	DFT	ab initio	Mg–Si	[3] Schick 2012	Table 3, p. 7, row 8 report
-15.4 kJ/mol-atom	Mg2Si	298.15	DFT	ab initio	Mg–Si	[3] Schick 2012	Table 3, p. 7, row 9 report
-21.1 kJ/mol-atom	Mg2Si	298.15	unspecified		Mg–Si	[3] Schick 2012	Table 3, p. 7, row 10 report
-21.1 kJ/mol-atom	Mg2Si	298.15	unspecified		Mg–Si	[3] Schick 2012 cites Feufel 1997 doi	Table 3, p. 7, row 4 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 Mg2Si
Value	Unit	Reading	Method (class, basis)	Effective
-61.9	kJ/mol-atom	0.05	4.2 (kems_vapour, calibrated)	4.2
-29.7	kJ/mol-atom	0.05	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-27.9	kJ/mol-atom	0.05	4.2 (kems_vapour, calibrated)	4.2
-27.1	kJ/mol-atom	0.05	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-26.67	kJ/mol-atom	0.001667	4.6 (emf, cleaned_below_threshold)	4.6
-26.4	kJ/mol-atom	0.05	4.6 (emf, cleaned_below_threshold)	4.6
-26.4	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-26.37	kJ/mol-atom	0.001667	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-26.3	kJ/mol-atom	0.01667	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-26	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-25.9	kJ/mol-atom	0.05	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-22.99	kJ/mol-atom	0.001667	4.2 (kems_vapour, calibrated)	4.2
-22.2	kJ/mol-atom	0.05	4.6 (emf, cleaned_below_threshold)	4.6
-22.16	kJ/mol-atom	0.001667	4.6 (emf, cleaned_below_threshold)	4.6
-21.1	kJ/mol-atom	0.01667	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-21.1	kJ/mol-atom	0.05	3.2 (solution_reaction_calorimetry, calibrated)	3.2
-14.21	kJ/mol-atom	0.001667	4.2 (kems_vapour, calibrated)	4.2
-14.2	kJ/mol-atom	0.05	4.2 (kems_vapour, calibrated)	4.2
-29.7	kJ/mol-atom	0.05	3.9 (model_calculated, calibrated)	3.9
-29.7	kJ/mol-atom	0.01667	3.9 (model_calculated, calibrated)	3.9
-26.47	kJ/mol-atom	0.001667	3.9 (model_calculated, calibrated)	3.9
-21.74	kJ/mol-atom	0.001667	3.9 (model_calculated, calibrated)	3.9
-21.37	kJ/mol-atom	0.001667	3.9 (model_calculated, calibrated)	3.9
-21.01	kJ/mol-atom	0.001667	3.9 (model_calculated, calibrated)	3.9
-21	kJ/mol-atom	0.05	3.9 (model_calculated, calibrated)	3.9
-18.2	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-17.7	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-17.7	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-16.7	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-15.4	kJ/mol-atom	0.05	9.966 (dft, calibrated)	9.966
-21.1	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-21.1	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 Mg2Si
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaacap	-12.42	-0.128725	Fm-3m	0	0	no
OQMD	oqmd-17649	-15.603	-0.161717	Fm-3m	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

Xiaoming Yuan, Weihua Sun, Yong Du, Dongdong Zhao, Huaming Yang, Thermodynamic modeling of the Mg–Si system with the Kaptay equation for the excess Gibbs energy of the liquid phase, Calphad 33, 673-678 (2009). doi:10.1016/j.calphad.2009.08.004
Xin-Yan Yan, Y. A. Chang, F. Zhang, A thermodynamic analysis of the Mg-Si system, JPE 21, 379-384 (2000). doi:10.1361/105497100770339914
Michael Schick, Bengt Hallstedt, Albert Glensk, Blazej Grabowski, Tilmann Hickel, Milan Hampl et al., Combined ab initio, experimental, and CALPHAD approach for an improved thermodynamic evaluation of the Mg–Si system, Calphad 37, 77-86 (2012). doi:10.1016/j.calphad.2012.02.001

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}
}