CaMg2: enthalpy of formation

15 accepted literature formation-enthalpy value(s) (experimental 9, model 2, DFT 1, unspecified 3); experimental median -13.17 kJ/mol-atom (n = 9); Materials Project -10.24 kJ/mol-atom (mp-aaaaadpo); OQMD -12.167 kJ/mol-atom (oqmd-21025).

Systems: Ca–Mg

Literature values

Enthalpy of formation of CaMg2 reported in the literature (15)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location	Quote
-14.59 kJ/mol-atom	Mg2Ca-C14	255.5	experimental		Ca–Mg	[1] Zhong 2006 cites Chiotti 1964 doi	Table 2, p. 4, row 13 report
-13.5 kJ/mol-atom	Mg2Ca	298.15	experimental		Ca–Mg	[2] Islam 2005 cites King 1964 doi	p. 11 report	In this study, the calculated enthalpy of formation of Mg2 Ca intermetallic compound at 298 K is -12.70 kJ/g atom, which is in close agreement with King and Kleppa [51] and Davison and Smith [52] who reported this value as -13.5 kJ/g atom and -13.17 kJ/g atom, respectively.
-13.5 kJ/mol-atom	Mg2Ca	298.15	experimental	experimental	Ca–Mg	[3] Kozlov 2008 cites King 1964 doi	Table 2, p. 5, row 4 report
-13.38 kJ/mol-atom	Mg2Ca-C14	298.15	experimental		Ca–Mg	[1] Zhong 2006 cites King 1964 doi	Table 2, p. 4, row 9 report
-13.17 kJ/mol-atom	Mg2Ca	298.15	experimental		Ca–Mg	[2] Islam 2005 cites Davison 1968	p. 11 report	In this study, the calculated enthalpy of formation of Mg2 Ca intermetallic compound at 298 K is -12.70 kJ/g atom, which is in close agreement with King and Kleppa [51] and Davison and Smith [52] who reported this value as -13.5 kJ/g atom and -13.17 kJ/g atom, respectively.
-13.04 kJ/mol-atom	Mg2Ca-C14	298.15	experimental		Ca–Mg	[1] Zhong 2006 cites Gartner 1965	Table 2, p. 4, row 10 report
-13 kJ/mol-atom	Mg2Ca	298.15	experimental	experimental	Ca–Mg	[3] Kozlov 2008 cites Davison 1968	Table 2, p. 5, row 6 report
-12.7 kJ/mol-atom	Mg2Ca	298.15	experimental	experimental	Ca–Mg	[3] Kozlov 2008 cites Gartner 1965	Table 2, p. 5, row 5 report
-11.29 kJ/mol-atom	Mg2Ca-C14	359	experimental		Ca–Mg	[1] Zhong 2006 cites Smith 1961	Table 2, p. 4, row 12 report
-12.85 kJ/mol-atom	Mg2Ca	298.15	model	Calphad	Ca–Mg	[3] Kozlov 2008 cites Agarwal 1995	Table 2, p. 5, row 2 report
-12.78 kJ/mol-atom	Mg2Ca	298.15	model	Calphad	Ca–Mg	[3] Kozlov 2008	Table 2, p. 5, row 3 report
-12.37 kJ/mol-atom	Mg2Ca	298.15	DFT	first-principles	Ca–Mg	[3] Kozlov 2008	Table 2, p. 5, row 1 report
-20.97 kJ/mol-atom	Mg2Ca-C14	0	unspecified		Ca–Mg	[1] Zhong 2006 cites Pyagai 1990	Table 2, p. 4, row 8 report
-13.04 kJ/mol-atom	Mg2Ca-C14	0	unspecified		Ca–Mg	[1] Zhong 2006 cites Davison 1968	Table 2, p. 4, row 11 report
-11.7161 kJ/mol-atom	Mg2Ca-C14	0	unspecified		Ca–Mg	[1] Zhong 2006	Table 2, p. 4, row 6 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 CaMg2
Value	Unit	Reading	Method (class, basis)	Effective
-14.59	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-13.5	kJ/mol-atom	0.05	3.5 (unknown, calibrated)	3.5
-13.5	kJ/mol-atom	0.05	4.1 (experimental_unspecified, cleaned_below_threshold)	4.1
-13.38	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-13.17	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-13.04	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-13	kJ/mol-atom	0.05	4.1 (experimental_unspecified, cleaned_below_threshold)	4.1
-12.7	kJ/mol-atom	0.05	4.1 (experimental_unspecified, cleaned_below_threshold)	4.1
-11.29	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-12.85	kJ/mol-atom	0.005	3.9 (model_calculated, calibrated)	3.9
-12.78	kJ/mol-atom	0.005	3.9 (model_calculated, calibrated)	3.9
-12.37	kJ/mol-atom	0.005	8.395 (dft, calibrated)	8.395
-20.97	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-13.04	kJ/mol-atom	0.005	3.5 (unknown, calibrated)	3.5
-11.7161	kJ/mol-atom	5.000e-5	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 CaMg2
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaadpo	-10.24	-0.106135	P6_3/mmc	0	0	no
OQMD	oqmd-21025	-12.167	-0.126104	P63/mmc	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

Yu Zhong, Jorge O. Sofo, Alan A. Luo, Zi-Kui Liu, Thermodynamics modeling of the Mg–Sr and Ca–Mg–Sr systems, Journal of Alloys and Compounds 421, 172-178 (2006). doi:10.1016/j.jallcom.2005.09.076
F. Islam, M. Medraj, The phase equilibria in the Mg–Ni–Ca system, Calphad 29, 289-302 (2005). doi:10.1016/j.calphad.2005.08.006
A. Kozlov, M. Ohno, R. Arroyave, Z.K. Liu, R. Schmid-Fetzer, Phase equilibria, thermodynamics and solidification microstructures of Mg–Sn–Ca alloys, Part 1: Experimental investigation and thermodynamic modeling of the ternary Mg–Sn–Ca system, Intermetallics 16, 299-315 (2008). doi:10.1016/j.intermet.2007.10.010

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}
}