# CaMg2: enthalpy of formation > Enthalpy of formation of CaMg2: 15 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID. HTML: https://data.orchid-project.org/compounds/CaMg2.html · Markdown: https://data.orchid-project.org/compounds/CaMg2.md 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](https://data.orchid-project.org/systems/CA-MG.html) ## Literature values Table: 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](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites Chiotti 1964_ [doi](https://doi.org/10.1016/0022-5088%2864%2990053-0) | Table 2, p. 4, row 13; `ORC-RZCL7BY52Z.730e2e` | | | -13.5 kJ/mol-atom | Mg2Ca | 298.15 | experimental | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [2] Islam 2005; _cites King 1964_ [doi](https://doi.org/10.1016/0001-6160%2864%2990056-2) | p. 11; `ORC-3LFXR22QOA.709ed5` | “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](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008; _cites King 1964_ [doi](https://doi.org/10.1016/0001-6160%2864%2990056-2) | Table 2, p. 5, row 4; `ORC-UWGNHDPS6J` | | | -13.38 kJ/mol-atom | Mg2Ca-C14 | 298.15 | experimental | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites King 1964_ [doi](https://doi.org/10.1016/0001-6160%2864%2990056-2) | Table 2, p. 4, row 9; `ORC-NICUD3CMK2.13630a` | | | -13.17 kJ/mol-atom | Mg2Ca | 298.15 | experimental | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [2] Islam 2005; _cites Davison 1968_ | p. 11; `ORC-3LFXR22QOA.15c12a` | “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](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites Gartner 1965_ | Table 2, p. 4, row 10; `ORC-IKPTGBFS7P.6f9e12` | | | -13 kJ/mol-atom | Mg2Ca | 298.15 | experimental | experimental | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008; _cites Davison 1968_ | Table 2, p. 5, row 6; `ORC-JZ4L4Q7U2N` | | | -12.7 kJ/mol-atom | Mg2Ca | 298.15 | experimental | experimental | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008; _cites Gartner 1965_ | Table 2, p. 5, row 5; `ORC-7O4OZG2DBF` | | | -11.29 kJ/mol-atom | Mg2Ca-C14 | 359 | experimental | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites Smith 1961_ | Table 2, p. 4, row 12; `ORC-MFXA4ERQYD.227b60` | | | -12.85 kJ/mol-atom | Mg2Ca | 298.15 | model | Calphad | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008; _cites Agarwal 1995_ | Table 2, p. 5, row 2; `ORC-XFTNAJZ22Q` | | | -12.78 kJ/mol-atom | Mg2Ca | 298.15 | model | Calphad | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008 | Table 2, p. 5, row 3; `ORC-S4AJ47FAEA` | | | -12.37 kJ/mol-atom | Mg2Ca | 298.15 | DFT | first-principles | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [3] Kozlov 2008 | Table 2, p. 5, row 1; `ORC-VKZEPFIM3R` | | | -20.97 kJ/mol-atom | Mg2Ca-C14 | 0 | unspecified | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites Pyagai 1990_ | Table 2, p. 4, row 8; `ORC-PZ7TZP7URJ.a0a8e2` | | | -13.04 kJ/mol-atom | Mg2Ca-C14 | 0 | unspecified | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006; _cites Davison 1968_ | Table 2, p. 4, row 11; `ORC-RGWLMRTDMG.5e2caf` | | | -11.7161 kJ/mol-atom | Mg2Ca-C14 | 0 | unspecified | | [Ca–Mg](https://data.orchid-project.org/systems/CA-MG.html) | [1] Zhong 2006 | Table 2, p. 4, row 6; `ORC-QFNUO7XCBY.c38408` | | ### Uncertainty budget Components kept separate, in the value's unit (literature [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md), [UNCERTAINTY_CALIBRATION.md](https://data.orchid-project.org/literature/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. Table: Uncertainty budget of the literature values of CaMg2 | Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | 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. Table: 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](https://doi.org/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](https://doi.org/10.1007/s11837-013-0755-4) (CC BY 4.0); ## Sources 1. 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](https://doi.org/10.1016/j.jallcom.2005.09.076) 2. 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](https://doi.org/10.1016/j.calphad.2005.08.006) 3. 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](https://doi.org/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). https://doi.org/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). https://doi.org/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). https://doi.org/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. ```bibtex @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} } ``` --- Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite ORCHID ([CITATION.cff](https://data.orchid-project.org/CITATION.cff)) and the original sources. Quotes are short excerpts kept so that each value can be checked; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full text are not redistributed. Field reference: [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt). Found an error? The report link of a value (Markdown: its id, ORC-..., in the Location column) opens a pre-filled GitHub issue, https://github.com/orchid-calphad/orchid-data/issues/new?template=report-value-error.yml&record_id=\, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).