Al4C3: enthalpy of formation

25 accepted literature formation-enthalpy value(s) (experimental 15, model 8, DFT 2); experimental median -26.2 kJ/mol-atom (n = 1); Materials Project -8.807 kJ/mol-atom (mp-aaaaacjf); OQMD -9.446 kJ/mol-atom (oqmd-646102).

Systems: Al–C

Literature values

Enthalpy of formation of Al4C3 reported in the literature (25)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-145.8 per mol-atom	Al4C3	298.15	experimental	Combustion calorimetry	Al–C	[1] Deffrennes 2019 cites Berthelot 1901	Table 5, p. 8, row 5 report
-132 per mol-atom	Al4C3	298.15	experimental	Combustion calorimetry	Al–C	[1] Deffrennes 2019 cites Thoburn 1964	Table 5, p. 8, row 4 report
-37.8 per mol-atom	Al4C3	298.15	experimental	Vapor-pressure measurements (2nd law)	Al–C	[1] Deffrennes 2019 cites Prescott 1928 doi	Table 5, p. 8, row 12 report
-36 per mol-atom	Al4C3	298.15	experimental	Vapor-pressure measurements (2nd law)	Al–C	[1] Deffrennes 2019 cites Prescott 1927 doi	Table 5, p. 8, row 11 report
-35.3 per mol-atom ± 3.3	Al4C3	298.15	experimental	Vapor-pressure measurements (2nd law)	Al–C	[1] Deffrennes 2019 cites Meschi 1959 doi	Table 5, p. 8, row 10 report
-35.2 per mol-atom ± 2.5	Al4C3	298.15	experimental	Vapor-pressure measurements (2nd law)	Al–C	[1] Deffrennes 2019 cites Potter 1966	Table 5, p. 8, row 9 report
-31.9 per mol-atom ± 1.2	Al4C3	298.15	experimental	Combustion calorimetry	Al–C	[1] Deffrennes 2019 cites Mah 1964	Table 5, p. 8, row 3 report
-30.6 per mol-atom ± 2.8	Al4C3	298.15	experimental	Vapor-pressure measurements (2nd law)	Al–C	[1] Deffrennes 2019 cites Plante 1966 doi	Table 5, p. 8, row 8 report
-29.7 per mol-atom ± 0.7	Al4C3	298.15	experimental	Combustion calorimetry	Al–C	[1] Deffrennes 2019 cites King 1964 doi	Table 5, p. 8, row 2 report
-29.6 per mol-atom ± 0.3	Al4C3	298.15	experimental	Solution calorimetry	Al–C	[1] Deffrennes 2019 cites Blachnik 1970 doi	Table 5, p. 8, row 6 report
-26.2 kJ/mol-atom	Al4C3	298.15	experimental	Experimental	Al–C	[1] Deffrennes 2019 cites Saba 1962	Table 7, p. 14, row 2 report
-24.9 per mol-atom ± 2.4	Al4C3	298.15	experimental	Vapor-pressure measurements (3nd law)	Al–C	[1] Deffrennes 2019 cites Rinehart 1980 doi	Table 5, p. 8, row 13 report
-23.9 per mol-atom ± 1.8	Al4C3	298.15	experimental	Combustion calorimetry	Al–C	[1] Deffrennes 2019 cites Meichsner 1934	Table 5, p. 8, row 1 report
-18.3 per mol-atom ± 1	Al4C3	298.15	experimental	Direct reaction calorimetry	Al–C	[1] Deffrennes 2019 cites Meschel 1995 doi	Table 5, p. 8, row 7 report
-17.9 per mol-atom ± 2.4	Al4C3	298.15	experimental	DTA (3rd law)	Al–C	[1] Deffrennes 2019 cites Thoburn 1964	Table 5, p. 8, row 14 report
-31.5 kJ/mol-atom	Al4C3	298.15	model	Thermodynamic assessment	Al–C	[1] Deffrennes 2019 cites ref. 15	Table 7, p. 14, row 4 report
-31.5 kJ/mol-atom	Al4C3	298.15	model	Calphad	Al–C	[2] He 2021 cites Grobner 1995 doi	Table 5, p. 12, row 4 report
-29.6 kJ/mol-atom	Al4C3	298.15	model	Thermodynamic assessment	Al–C	[1] Deffrennes 2019 cites ref. 14	Table 7, p. 14, row 3 report
-29.6 kJ/mol-atom	Al4C3	298.15	model	Thermodynamic assessment	Al–C	[1] Deffrennes 2019 cites ref. 17	Table 7, p. 14, row 5 report
-29.6 kJ/mol-atom	Al4C3	298.15	model	Calphad	Al–C	[2] He 2021 cites Caian 1994	Table 5, p. 12, row 3 report
-28.5 kJ/mol-atom	Al4C3	298.15	model	Calphad	Al–C	[2] He 2021	Table 5, p. 12, row 6 report
-27.6 kJ/mol-atom	Al4C3	298.15	model	Thermodynamic assessment	Al–C	[1] Deffrennes 2019	Table 7, p. 14, row 6 report
-27.6 kJ/mol-atom	Al4C3	298.15	model	Calphad	Al–C	[2] He 2021 cites Deffrennes 2019 doi	Table 5, p. 12, row 5 report
-26.4 kJ/mol-atom	Al4C3	298.15	DFT	DFT	Al–C	[2] He 2021 cites Pisch 2020	Table 5, p. 12, row 1 report
-26.2 per mol-atom	Al4C3	298.15	DFT	DFT (SCAN functional)	Al–C	[1] Deffrennes 2019 cites Pisch 2019	Table 5, p. 8, row 15 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 Al4C3
Value	Unit	Printed	Reading	Method (class, basis)	Effective
-145.8	per mol-atom		0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-132	per mol-atom		0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-37.8	per mol-atom		0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-36	per mol-atom		0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom
-35.3	per mol-atom	3.3	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	3.3
-35.2	per mol-atom	2.5	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	2.5
-31.9	per mol-atom	1.2	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	1.2
-30.6	per mol-atom	2.8	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	2.8
-29.7	per mol-atom	0.7	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	0.7
-29.6	per mol-atom	0.3	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	0.3
-26.2	kJ/mol-atom		0.05	4.1 (experimental_unspecified, cleaned_below_threshold)	4.1
-24.9	per mol-atom	2.4	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	2.4
-23.9	per mol-atom	1.8	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	1.8
-18.3	per mol-atom	1	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	1
-17.9	per mol-atom	2.4	0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	2.4
-31.5	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-31.5	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-29.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-29.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-29.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-28.5	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-27.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-27.6	kJ/mol-atom		0.05	3.9 (model_calculated, calibrated)	3.9
-26.4	kJ/mol-atom		0.05	9.966 (dft, calibrated)	9.966
-26.2	per mol-atom		0.05	unit 'per mol-atom' not convertible to kJ/mol-atom	unit 'per mol-atom' not convertible to kJ/mol-atom

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 Al4C3
Source	Entry	kJ/mol-atom	eV/atom	Space group	E above hull (kJ/mol-atom)	E above hull (eV/atom)	Theoretical
Materials Project	mp-aaaaacjf	-8.807	-0.091274	R-3m	0	0	no
OQMD	oqmd-646102	-9.446	-0.097902	R3m	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

G. Deffrennes, B. Gardiola, M. Allam, D. Chaussende, A. Pisch, J. Andrieux et al., Critical assessment and thermodynamic modeling of the Al–C system, Calphad 66, 101648 (2019). doi:10.1016/j.calphad.2019.101648
Zhangting He, Bartek Kaplan, Huahai Mao, Malin Selleby, The third generation Calphad description of Al–C including revisions of pure Al and C, Calphad 72, 102250 (2021). doi:10.1016/j.calphad.2021.102250

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}
}