Mg–O system

35 accepted literature values from 3 paper(s) (experimental 8, model 20, DFT 3, unspecified 4); 2 calculated phase diagram(s). 1 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: JSON · CSV · interactive explorer · interactive phase diagram · phases (8) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	8
model	20
DFT	3
unspecified	4

Accepted values by property group
Property group	Values
phase transition	1
phase equilibrium	26
formation	5
heat capacity / entropy / enthalpy	3

Calculated phase diagrams

Binary phase diagrams calculated with pycalphad 0.11.2 from the SGTE binary collection (Hallstedt 2025, CC BY 4.0). Evidence class: model.

Assessments with a calculated phase diagram
TDB file	Assessment	SHA-256	Links
MgO-18Lia.tdb	S.-M. Liang, R. Schmid-Fetzer, J. Eur. Ceram. Soc., 38, 4768-85(2018). doi:10.1016/j.jeurceramsoc.2018.06.015	`28bd068049e41b579b0e2a29e75feb9e8ac64c72b5b2fa8daa7bfae24147c334`	viewer · TDB · JSON
MgO-23Li.tdb	X.-J. Li, S.-H. Liu, J. Mining Metall. B, 59, 395-405(2023). doi:10.2298/JMMB230621034L	`d795b07d34aedd0d85468125fa5ec66c6e7f72b88dcc68b79c61adaf4cfbbb95`	viewer · TDB · JSON

Convex hulls: Materials Project DFT hull · OQMD DFT hull · CALPHAD hull MgO-18Lia · CALPHAD hull MgO-93Hal-LB

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, Mg–O system (5)
Phase	Compound	Value	T (K)	Class	MP DFT (kJ/mol-atom)	OQMD DFT (kJ/mol-atom)	Source	Location	Quote
MgO		-602 kJ/(mol 0)	298.15	experimental			[1] Hallstedt 1993 cites Fikner	p. 5 report	However, Fikner [5J and Otsuka and Kozuka [6J have found correlations between the enthalpy and entropy of dissolution of 0 into liquid metals and the enthalpy of formation of the oxide at 298 K. Using the expressions provided by Fitzner I5J with the enthalpy of formation of MgO (A?&s = -602 kJ/(mol 0)) gives A"G = -500000 + 90T J/mol for dissolution of 0 in liquid Mg (1 mol-W standard state).
MgO	MgO	-300.62 kJ/mol-atom		model	-294.608 (mp-aaaaabwr)	-284.268 (oqmd-1443261)	[2] Li 2023	Table 5, p. 6, row 1 report
MgO		-282.82 kJ/mol-atom		DFT			[2] Li 2023	Table 3, p. 5, row 2 report
MgO		-281.86 kJ/mol-atom	0	DFT			[2] Li 2023	Table 3, p. 5, row 1 report
MgO		-263.71 kJ/mol-atom		DFT			[2] Li 2023	Table 3, p. 5, row 3 report

Other properties

Phase transition (1)

Phase transition, Mg–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Phase transition	3249.6 K	3249.6	congruent transformation	model	[3] Liang 2018	p. 11 report	This stable range of liquid oxide extends from 49.98 to 50.01 at.% O at 1 bar with a calculated congruent melting point of MgO at 3249.6 K.

Phase equilibrium (26)

Phase equilibrium, Mg–O system
Property	T (K)	Phases / composition	Class	Source	Location
Phase composition	923	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Fikner	Table 2, p. 6, row 2 report
Phase composition	923	liquid Mg liquid Mg: Mg 1, O 0	unspecified	[1] Hallstedt 1993	Table 2, p. 6, row 1 report
Phase composition	923	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Otsuka 1981	Table 2, p. 6, row 3 report
Phase composition	1000	liquid Mg liquid Mg: Mg 1, O 0	unspecified	[1] Hallstedt 1993	Table 2, p. 6, row 4 report
Phase composition	1000	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Otsuka 1981	Table 2, p. 6, row 6 report
Phase composition	1000	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Fikner	Table 2, p. 6, row 5 report
Phase composition	1200	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Otsuka 1981	Table 2, p. 6, row 9 report
Phase composition	1200	liquid Mg liquid Mg: Mg 0.999996, O 4.000e-6	model	[1] Hallstedt 1993 cites Fikner	Table 2, p. 6, row 8 report
Phase composition	1200	liquid Mg liquid Mg: Mg 1, O 0	unspecified	[1] Hallstedt 1993	Table 2, p. 6, row 7 report
Phase composition	1373	liquid Mg liquid Mg: Mg 1, O 0	model	[1] Hallstedt 1993 cites Otsuka 1981	Table 2, p. 6, row 12 report
Phase composition	1373	liquid Mg liquid Mg: Mg 0.999998, O 2.000e-6	unspecified	[1] Hallstedt 1993	Table 2, p. 6, row 10 report
Phase composition	1373	liquid Mg liquid Mg: Mg 0.999986, O 1.400e-5	model	[1] Hallstedt 1993 cites Fikner	Table 2, p. 6, row 11 report
Phase composition	2647.5	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Ruff 1913 doi	Table 4, p. 8, row 1 report
Phase composition	3073	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Riley 1966	Table 4, p. 8, row 4 report
Phase composition	3073	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Kanolt 1913	Table 4, p. 8, row 2 report
Phase composition	3096	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Panek 1979	Table 4, p. 8, row 5 report
Phase composition	3098	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites McNally 1961	Table 4, p. 8, row 3 report
Phase composition	3098	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites Factsage 2017	Table 4, p. 8, row 12 report
Phase composition	3099	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites Hlavac 1982 doi	Table 4, p. 8, row 8 report
Phase composition	3100	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites SGTE 2013	Table 4, p. 8, row 13 report
Phase composition	3100	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites Wriedt 1987 doi	Table 4, p. 8, row 9 report
Phase composition	3105	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites Chase 1998	Table 4, p. 8, row 11 report
Phase composition	3105	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018 cites Kubaschewski 1993	Table 4, p. 8, row 10 report
Phase composition	3215	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Chernyshev 1993 doi	Table 4, p. 8, row 6 report
Phase composition	3250	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	experimental	[3] Liang 2018 cites Ronchi 2001 doi	Table 4, p. 8, row 7 report
Phase composition	3250	congruent melting: MgO liquid: O 0.5; MgO: O 0.5	model	[3] Liang 2018	Table 4, p. 8, row 14 report

Heat capacity / entropy / enthalpy (3)

Heat capacity / entropy / enthalpy, Mg–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Entropy printed: Standard entropy	28.1 J/mol (basis unstated)/K		MgO alloy: Mg 0.5, O 0.5	model	[2] Li 2023	Table 5, p. 6, row 1 report
Heat capacity printed: Heat capacity of the liquid oxide	33.47 J/mol-atom/K		liquid oxide alloy: Mg 0.5, O 0.5	model	[2] Li 2023	Table 5, p. 6, row 1 report
Heat capacity printed: Heat capacity at 298.15 K	18.65 J/mol-atom/K	298.15	MgO alloy: Mg 0.5, O 0.5	model	[2] Li 2023	Table 5, p. 6, row 1 report

Sources

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

Bengt Hallstedt, The Magnesium — Oxygen system, Calphad 17, 281-286 (1993). doi:10.1016/0364-5916(93)90006-w
X.-J. Li, S.-H. Liu, Thermodynamic description of the Mg-O and Al-O systems, J min metall B Metall 59, 395-405 (2023). doi:10.2298/jmmb230621034l
Song-Mao Liang, Rainer Schmid-Fetzer, Complete thermodynamic description of the Mg-Ca-O phase diagram including the Ca-O, Mg-O and CaO-MgO subsystems, Journal of the European Ceramic Society 38, 4768-4785 (2018). doi:10.1016/j.jeurceramsoc.2018.06.015

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-Diagrams: calculated binary phase diagrams (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735859
R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735891
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_phase_diagrams_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Diagrams: calculated binary phase diagrams}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735859},
  url       = {https://doi.org/10.5281/zenodo.23735859}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@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}
}