# Ag2Se: enthalpy of formation

> Enthalpy of formation of Ag2Se: 24 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/Ag2Se.html · Markdown: https://data.orchid-project.org/compounds/Ag2Se.md

24 accepted literature formation-enthalpy value(s) (experimental 14, model 2, DFT 8); experimental median -13.623 kJ/mol-atom (n = 14); Materials Project -21.663 kJ/mol-atom (mp-aaabgjqe); OQMD -7.938 kJ/mol-atom (oqmd-1374449).

Systems: [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html)

## Literature values

Table: Enthalpy of formation of Ag2Se reported in the literature (24)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -14.3633 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Voronin 2011_ [doi](https://doi.org/10.1134/s1023193511040203) | Table 1, p. 3, row 4; `ORC-IAHORPYKKP.ee26d1` |  |
| -14.2433 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Osadchii 2007_ [doi](https://doi.org/10.2138/am.2007.2209) | Table 1, p. 3, row 1; `ORC-DENBWB3K3C.f053d3` |  |
| -14.2333 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Nasar 1997_ [doi](https://doi.org/10.1007/s11663-997-0120-5) | Table 1, p. 3, row 15; `ORC-FORFJG353E.50f713` |  |
| -14.2333 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Nasar 1997_ [doi](https://doi.org/10.1007/s11663-997-0120-5) | Table 1, p. 3, row 2; `ORC-NOQDCUENTV.b287ad` |  |
| -14.1367 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Voronin 2011_ [doi](https://doi.org/10.1134/s1023193511040203) | Table 1, p. 3, row 3; `ORC-IYYBFJIDJR.5ed8ac` |  |
| -14.12 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Grnvold 2003_ [doi](https://doi.org/10.1016/s0040-6031%2802%2900470-7) | Table 1, p. 3, row 7; `ORC-S7IJ2WTKZG.8ae02e` |  |
| -13.7067 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Feng 2013_ [doi](https://doi.org/10.1016/j.ssi.2012.10.013) | Table 1, p. 3, row 8; `ORC-3HNT2KROYM.68a880` |  |
| -13.54 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Oehsen 1981_ [doi](https://doi.org/10.1002/bbpc.19810850104) | Table 1, p. 3, row 5; `ORC-N7ZOMZ7UNS.c3fba0` |  |
| -13.3667 kJ/mol-atom | α-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Olin 2005_ | Table 1, p. 3, row 6; `ORC-RMJA7ZD7GC.11b1bd` |  |
| -11.6867 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Feng 2013_ [doi](https://doi.org/10.1016/j.ssi.2012.10.013) | Table 1, p. 3, row 13; `ORC-JFXIVMRCAO.aecbc9` |  |
| -11.6833 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Grnvold 2003_ [doi](https://doi.org/10.1016/s0040-6031%2802%2900470-7) | Table 1, p. 3, row 12; `ORC-IR25DWRF5G.7f35b1` |  |
| -11.68 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Voronin 2011_ [doi](https://doi.org/10.1134/s1023193511040203) | Table 1, p. 3, row 11; `ORC-FCNMFTUR4E.f22bb3` |  |
| -11.6733 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Osadchii 2007_ [doi](https://doi.org/10.2138/am.2007.2209) | Table 1, p. 3, row 10; `ORC-DYLEZCG4HM.87c197` |  |
| -11.6667 kJ/mol-atom | β-Ag2Se | 298.15 | experimental |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018; _cites Oehsen 1981_ [doi](https://doi.org/10.1002/bbpc.19810850104) | Table 1, p. 3, row 14; `ORC-PJHC2KGG2M.da54bd` |  |
| -14.2433 kJ/mol-atom | α-Ag2Se | 298.15 | model |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 1, p. 3, row 9; `ORC-EG4CZFRGL7.4223e1` |  |
| -11.67 kJ/mol-atom | β-Ag2Se | 298.15 | model |  | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 1, p. 3, row 16; `ORC-G2E5AOIVAY.1d15e8` |  |
| -9.936 kJ/mol-atom | α-Ag2Se |  | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 1; `ORC-BC2LZ73AND.5a2061` |  |
| -9.936 kJ/mol-atom | α-Ag₂Se | 0 | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 1; `ORC-BC2LZ73AND.e8e3fd` |  |
| -5.869 kJ/mol-atom | α-Ag2Se |  | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 2; `ORC-UZUVCSCTEU.6ee1ba` |  |
| -5.869 kJ/mol-atom | α-Ag₂Se | 0 | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 2; `ORC-UZUVCSCTEU.c30a3c` |  |
| -4.127 kJ/mol-atom | β-Ag2Se |  | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 7; `ORC-QDB2TFAHB5.03d7af` |  |
| -4.127 kJ/mol-atom | β-Ag₂Se | 0 | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 7; `ORC-QDB2TFAHB5.10dd99` |  |
| -3.196 kJ/mol-atom | β-Ag2Se |  | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 8; `ORC-5Y5PRUZMB2.3ca8e9` |  |
| -3.196 kJ/mol-atom | β-Ag₂Se | 0 | DFT | DFT | [Ag–Se](https://data.orchid-project.org/systems/AG-SE.html) | [1] Li 2018 | Table 4, p. 6, row 8; `ORC-5Y5PRUZMB2.c05b32` |  |

### 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 Ag2Se

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -14.3633 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.2433 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.2333 | kJ/mol-atom |  | 0.01667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.2333 | kJ/mol-atom |  | 0.01667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.1367 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.12 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -13.7067 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -13.54 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -13.3667 | kJ/mol-atom |  | 0.01667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -11.6867 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -11.6833 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -11.68 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -11.6733 | kJ/mol-atom |  | 0.001667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -11.6667 | kJ/mol-atom |  | 0.01667 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -14.2433 | kJ/mol-atom |  | 0.001667 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -11.67 | kJ/mol-atom |  | 0.001667 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -9.936 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -9.936 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -5.869 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -5.869 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -4.127 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -4.127 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -3.196 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -3.196 | kJ/mol-atom |  | 5.000e-4 | 9.966 (dft, calibrated) |  |  |  | 9.966 |

## 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 Ag2Se

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaabgjqe | -21.663 | -0.224522 | P2_12_12_1 | 0 | 0 | no |
| OQMD | oqmd-1374449 | -7.938 | -0.082276 | Cmcm | 0 | 0 | yes |

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. Zhi Li, Shun-Li Shang, Jianyun Shen, Po-Hsien Liao, Zi-Kui Liu, Timothy J. Anderson, Thermodynamic Assessment of the Ag-Se System Aided by First-Principles Calculations, J. Phase Equilib. Diffus. 39, 870-881 (2018). [doi:10.1007/s11669-018-0683-7](https://doi.org/10.1007/s11669-018-0683-7)

## 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/).