# Ca2Pb: enthalpy of formation

> Enthalpy of formation of Ca2Pb: 7 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/Ca2Pb.html · Markdown: https://data.orchid-project.org/compounds/Ca2Pb.md

7 accepted literature formation-enthalpy value(s) (experimental 4, model 3); experimental median -59 kJ/mol-atom (n = 4); Materials Project -53.157 kJ/mol-atom (mp-aaaabtcg); OQMD -54.694 kJ/mol-atom (oqmd-10998).

Systems: [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html)

## Literature values

Table: Enthalpy of formation of Ca2Pb reported in the literature (7)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -62 kJ/mol-atom ± 2 | Ca2Pb | 300 | experimental | Solution calorimetry | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [1] Idbenali 2008; _cites Sommer 2006_ [doi](https://doi.org/10.1016/j.intermet.2005.06.003) | Table 5, p. 8, row 1; `ORC-DRQY4EDHMG` |  |
| -59 kJ/mol-atom ± 1.5 | Ca2Pb | 300 | experimental | Dissolution calorimetry | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [1] Idbenali 2008; _cites Bouirden 1984_ | Table 5, p. 8, row 3; `ORC-INPTZVNKKX` |  |
| -59 kJ/mol-atom ± 5 | Ca2Pb | 300 | experimental | Solution calorimetry | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [1] Idbenali 2008; _cites Notin 1989_ [doi](https://doi.org/10.1016/0022-5088%2889%2990177-x) | Table 5, p. 8, row 2; `ORC-NTVCF44WPZ` |  |
| -59 kJ/mol-atom ± 1.5 | Ca2Pb | 300 | experimental | dissolution calorimetry | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [2] Cartigny 2004; _cites Bouirden 1984_ | Table 2, p. 3, row 7; `ORC-RX7ZVH6AKG` |  |
| -69.577 kJ/mol-atom | Ca2Pb | 300 | model |  | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [2] Cartigny 2004 | Table 2, p. 3, row 8; `ORC-26OFWWHHVQ` |  |
| -69.577 kJ/mol-atom | Ca2Pb | 300 | model | Optimization | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [1] Idbenali 2008; _cites Cartigny 2004_ [doi](https://doi.org/10.1016/j.tca.2004.01.001) | Table 5, p. 8, row 4; `ORC-RTPSUJ6ZCH` |  |
| -66.305 kJ/mol-atom | Ca2Pb | 300 | model | Optimization | [Ca–Pb](https://data.orchid-project.org/systems/CA-PB.html) | [1] Idbenali 2008 | Table 5, p. 8, row 5; `ORC-FPAY4SRRJJ` |  |

### 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 Ca2Pb

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -62 | kJ/mol-atom | 2 | 0.5 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -59 | kJ/mol-atom | 1.5 | 0.5 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -59 | kJ/mol-atom | 5 | 0.5 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 5 |
| -59 | kJ/mol-atom | 1.5 | 0.05 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -69.577 | kJ/mol-atom |  | 5.000e-4 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -69.577 | kJ/mol-atom |  | 5.000e-4 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -66.305 | kJ/mol-atom |  | 5.000e-4 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |

## 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 Ca2Pb

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaaabtcg | -53.157 | -0.550939 | Pnma | 0 | 0 | no |
| OQMD | oqmd-10998 | -54.694 | -0.566865 | Pnma | 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. M. Idbenali, C. Servant, N. Selhaoui, L. Bouirden, A thermodynamic reassessment of the Ca–Pb system, Calphad 32, 64-73 (2008). [doi:10.1016/j.calphad.2007.10.004](https://doi.org/10.1016/j.calphad.2007.10.004)
2. Y. Cartigny, J.M. Fiorani, A. Maı̂tre, M. Vilasi, Thermodynamic assessment of the Ca–Pb system, Thermochimica Acta 414, 197-202 (2004). [doi:10.1016/j.tca.2004.01.001](https://doi.org/10.1016/j.tca.2004.01.001)

## 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/).