# Al4C3: enthalpy of formation

> Enthalpy of formation of Al4C3: 25 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/Al4C3.html · Markdown: https://data.orchid-project.org/compounds/Al4C3.md

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](https://data.orchid-project.org/systems/AL-C.html)

## Literature values

Table: Enthalpy of formation of Al4C3 reported in the literature (25)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -145.8 per mol-atom | Al4C3 | 298.15 | experimental | Combustion calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Berthelot 1901_ | Table 5, p. 8, row 5; `ORC-GQPALVE3FM` |  |
| -132 per mol-atom | Al4C3 | 298.15 | experimental | Combustion calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Thoburn 1964_ | Table 5, p. 8, row 4; `ORC-WJX3KBYI4D` |  |
| -37.8 per mol-atom | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (2nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Prescott 1928_ [doi](https://doi.org/10.1021/ja01399a011) | Table 5, p. 8, row 12; `ORC-LQ44ALDXCA` |  |
| -36 per mol-atom | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (2nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Prescott 1927_ [doi](https://doi.org/10.1021/ja01410a013) | Table 5, p. 8, row 11; `ORC-KZPVUBQEW7` |  |
| -35.3 per mol-atom ± 3.3 | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (2nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Meschi 1959_ [doi](https://doi.org/10.1021/j150577a036) | Table 5, p. 8, row 10; `ORC-KZH6WOVWPK` |  |
| -35.2 per mol-atom ± 2.5 | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (2nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Potter 1966_ | Table 5, p. 8, row 9; `ORC-RQDJFQ36NB` |  |
| -31.9 per mol-atom ± 1.2 | Al4C3 | 298.15 | experimental | Combustion calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Mah 1964_ | Table 5, p. 8, row 3; `ORC-NTHYKQOUBA` |  |
| -30.6 per mol-atom ± 2.8 | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (2nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Plante 1966_ [doi](https://doi.org/10.6028/jres.070a.022) | Table 5, p. 8, row 8; `ORC-OZKYPTQ22G` |  |
| -29.7 per mol-atom ± 0.7 | Al4C3 | 298.15 | experimental | Combustion calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites King 1964_ [doi](https://doi.org/10.6028/jres.068a.066) | Table 5, p. 8, row 2; `ORC-UGP2PYPITH` |  |
| -29.6 per mol-atom ± 0.3 | Al4C3 | 298.15 | experimental | Solution calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Blachnik 1970_ [doi](https://doi.org/10.1039/tf9706601058) | Table 5, p. 8, row 6; `ORC-NTIBNHM7MY` |  |
| -26.2 kJ/mol-atom | Al4C3 | 298.15 | experimental | Experimental | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Saba 1962_ | Table 7, p. 14, row 2; `ORC-GCZG5SCLHX.5e1ccb` |  |
| -24.9 per mol-atom ± 2.4 | Al4C3 | 298.15 | experimental | Vapor-pressure measurements (3nd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Rinehart 1980_ [doi](https://doi.org/10.1016/0021-9614%2880%2990038-5) | Table 5, p. 8, row 13; `ORC-5GKUJVO3DV` |  |
| -23.9 per mol-atom ± 1.8 | Al4C3 | 298.15 | experimental | Combustion calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Meichsner 1934_ | Table 5, p. 8, row 1; `ORC-UMVJIJX2EX` |  |
| -18.3 per mol-atom ± 1 | Al4C3 | 298.15 | experimental | Direct reaction calorimetry | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Meschel 1995_ [doi](https://doi.org/10.1016/0925-8388%2895%2901649-x) | Table 5, p. 8, row 7; `ORC-AUPWRUCYCF` |  |
| -17.9 per mol-atom ± 2.4 | Al4C3 | 298.15 | experimental | DTA (3rd law) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Thoburn 1964_ | Table 5, p. 8, row 14; `ORC-UCQMWKVVOH` |  |
| -31.5 kJ/mol-atom | Al4C3 | 298.15 | model | Thermodynamic assessment | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites ref. 15_ | Table 7, p. 14, row 4; `ORC-F4FQS6ZE2X.80b3dc` |  |
| -31.5 kJ/mol-atom | Al4C3 | 298.15 | model | Calphad | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [2] He 2021; _cites Grobner 1995_ [doi](https://doi.org/10.1016/0925-8388%2894%2906028-2) | Table 5, p. 12, row 4; `ORC-WBRE5IQO2U.d04a72` |  |
| -29.6 kJ/mol-atom | Al4C3 | 298.15 | model | Thermodynamic assessment | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites ref. 14_ | Table 7, p. 14, row 3; `ORC-3RHBCVCIQM.a68f55` |  |
| -29.6 kJ/mol-atom | Al4C3 | 298.15 | model | Thermodynamic assessment | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites ref. 17_ | Table 7, p. 14, row 5; `ORC-6FX4ADI5V6.6c04e7` |  |
| -29.6 kJ/mol-atom | Al4C3 | 298.15 | model | Calphad | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [2] He 2021; _cites Caian 1994_ | Table 5, p. 12, row 3; `ORC-NM6YKB7I4E.c9bb7d` |  |
| -28.5 kJ/mol-atom | Al4C3 | 298.15 | model | Calphad | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [2] He 2021 | Table 5, p. 12, row 6; `ORC-6Z5DBOUA7Y.d38350` |  |
| -27.6 kJ/mol-atom | Al4C3 | 298.15 | model | Thermodynamic assessment | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019 | Table 7, p. 14, row 6; `ORC-242BY7NNE5.f80c95` |  |
| -27.6 kJ/mol-atom | Al4C3 | 298.15 | model | Calphad | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [2] He 2021; _cites Deffrennes 2019_ [doi](https://doi.org/10.1016/j.calphad.2019.101648) | Table 5, p. 12, row 5; `ORC-2HP5YAQZUL.6c5487` |  |
| -26.4 kJ/mol-atom | Al4C3 | 298.15 | DFT | DFT | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [2] He 2021; _cites Pisch 2020_ | Table 5, p. 12, row 1; `ORC-FPO25HWMW3.eae256` |  |
| -26.2 per mol-atom | Al4C3 | 298.15 | DFT | DFT (SCAN functional) | [Al–C](https://data.orchid-project.org/systems/AL-C.html) | [1] Deffrennes 2019; _cites Pisch 2019_ | Table 5, p. 8, row 15; `ORC-5S5UTGWFCL` |  |

### 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 Al4C3

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | 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.

Table: 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](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. 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](https://doi.org/10.1016/j.calphad.2019.101648)
2. 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](https://doi.org/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). 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=\<id>, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).