# CeC2: enthalpy of formation

> Enthalpy of formation of CeC2: 8 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/CeC2.html · Markdown: https://data.orchid-project.org/compounds/CeC2.md

8 accepted literature formation-enthalpy value(s) (experimental 8); experimental median -30.4 kJ/mol-atom (n = 8); Materials Project -15.378 kJ/mol-atom (mp-aaaaaeff); OQMD -8.01 kJ/mol-atom (oqmd-13373).

Systems: [C–Ce](https://data.orchid-project.org/systems/C-CE.html)

## Literature values

Table: Enthalpy of formation of CeC2 reported in the literature (8)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -40.03 kJ/mol-atom ± 3.7 | CeC2 | 298.15 | experimental | Dynamic effusion MS | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Vidhya 2003_ [doi](https://doi.org/10.1016/s0022-3115%2803%2900071-0) | Table 2, p. 2, row 16; `ORC-UPE37JFFSG.27e28e` |  |
| -34.9 kJ/mol-atom | CeC2 | 298.15 | experimental | Knudsen effusion | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Faircloth 1968_ [doi](https://doi.org/10.1016/0022-1902%2868%2980476-2) | Table 2, p. 2, row 15; `ORC-JQOKSVUD7L` |  |
| -32.4 kJ/mol-atom ± 1.8 | CeC2 | 298.15 | experimental | Bomb calorimetry | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Baker 1971_ [doi](https://doi.org/10.1016/s0021-9614%2871%2980068-x) | Table 2, p. 2, row 14; `ORC-G6NSZLCZ6G.8b7d6b` |  |
| -31.3 kJ/mol-atom | CeC2 | 298.15 | experimental | Controlled CO pressure | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Pialoux 1988_ [doi](https://doi.org/10.1016/0022-5088%2888%2990046-x) | Table 2, p. 2, row 13; `ORC-VQHVGJKEGN` |  |
| -29.5 kJ/mol-atom ± 3.5 | CeC2 | 298.15 | experimental | emf | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Anderson 2011_ | Table 2, p. 2, row 12; `ORC-33HYQ2NTQM.39f3d1` |  |
| -27.2 kJ/mol-atom | CeC2 | 298.15 | experimental | Knudsen cell MS | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Winchell 1967_ [doi](https://doi.org/10.1021/j100872a050) | Table 2, p. 2, row 10; `ORC-7ZU55J4DMS` |  |
| -25.4 kJ/mol-atom ± 1.4 | CeC2 | 298.15 | experimental | Synthesis calorimetry | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Meschel 1995_ [doi](https://doi.org/10.1016/0925-8388%2894%2906009-6) | Table 2, p. 2, row 11; `ORC-IJVD6G4UC3.004536` |  |
| -20.9 kJ/mol-atom ± 7 | CeC2 | 298.15 | experimental | Knudsen cell MS | [C–Ce](https://data.orchid-project.org/systems/C-CE.html) | [1] Peng 2011; _cites Balducci 1969_ | Table 2, p. 2, row 9; `ORC-LYASWSGJGJ.1deb6c` |  |

### 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 CeC2

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -40.03 | kJ/mol-atom | 3.7 | 0.005 | 4.2 (kems_vapour, calibrated) |  |  |  | 4.2 |
| -34.9 | kJ/mol-atom |  | 0.05 | 4.2 (kems_vapour, calibrated) |  |  |  | 4.2 |
| -32.4 | kJ/mol-atom | 1.8 | 0.05 | 1 (combustion_calorimetry, cleaned_below_threshold) |  |  |  | 1.8 |
| -31.3 | kJ/mol-atom |  | 0.05 | 4.1 (experimental_unspecified, cleaned_below_threshold) |  |  |  | 4.1 |
| -29.5 | kJ/mol-atom | 3.5 | 0.05 | 4.6 (emf, cleaned_below_threshold) |  |  |  | 4.6 |
| -27.2 | kJ/mol-atom |  | 0.05 | 4.2 (kems_vapour, calibrated) |  |  |  | 4.2 |
| -25.4 | kJ/mol-atom | 1.4 | 0.05 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -20.9 | kJ/mol-atom | 7 | 0.05 | 4.2 (kems_vapour, calibrated) |  |  |  | 7 |

## 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 CeC2

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaaaaeff | -15.378 | -0.159383 | I4/mmm | 5.1766 | 0.0537 | no |
| OQMD | oqmd-13373 | -8.01 | -0.08302 | I4/mmm | 1.2254 | 0.0127 | 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. Yingbiao Peng, Yong Du, Lijun Zhang, Chunsheng Sha, Shuhong Liu, Feng Zheng et al., Thermodynamic modeling of the C–RE (RE=La, Ce and Pr) systems, Calphad 35, 533-541 (2011). [doi:10.1016/j.calphad.2011.09.002](https://doi.org/10.1016/j.calphad.2011.09.002)

## 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/).