# Si2Sr: enthalpy of formation

> Enthalpy of formation of Si2Sr: 16 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/Si2Sr.html · Markdown: https://data.orchid-project.org/compounds/Si2Sr.md

16 accepted literature formation-enthalpy value(s) (experimental 4, model 1, DFT 10, unspecified 1); experimental median -41.5 kJ/mol-atom (n = 4); Materials Project -30.715 kJ/mol-atom (mp-aaaaacol); OQMD -35.357 kJ/mol-atom (oqmd-6867).

Systems: [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html)

## Literature values

Table: Enthalpy of formation of Si2Sr reported in the literature (16)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -42.7 kJ/mol-atom | α-SrSi2 | 298.15 | experimental |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Balducci 2006_ [doi](https://doi.org/10.1016/j.intermet.2005.10.008) | Table 2, p. 4, row 22; `ORC-GBX5IRSDAR.72bc1a` |  |
| -42.7 kJ/mol-atom ± 4.3 | α-Si2Sr | 298.15 | experimental |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Balducci 2006_ [doi](https://doi.org/10.1016/j.intermet.2005.10.008) | Table 2, p. 2, row 13; `ORC-MNLYH6ZXTW.6fcbcb` |  |
| -40.3 kJ/mol-atom ± 3.7 | β-Si2Sr | 298.15 | experimental |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Balducci 2006_ [doi](https://doi.org/10.1016/j.intermet.2005.10.008) | Table 2, p. 2, row 10; `ORC-43L5PTAVQT.7b5c82` |  |
| -40.3 kJ/mol-atom | β-SrSi2 | 298.15 | experimental |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Balducci 2006_ [doi](https://doi.org/10.1016/j.intermet.2005.10.008) | Table 2, p. 4, row 26; `ORC-GNQ4UPZMQ2.923e00` |  |
| -67.3 kJ/mol-atom | α-SrSi2 | 298.15 | model |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Gordienko 1997_ [doi](https://doi.org/10.1007/bf02680502) | Table 2, p. 4, row 17; `ORC-E7O5G4FDT6.3154b4` |  |
| -44.7 kJ/mol-atom | β-SrSi2 | 298.15 | DFT | first-principles LDA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009 | Table 2, p. 4, row 23; `ORC-CDZ7HLXDBU.ca7693` |  |
| -44.7 kJ/mol-atom | β-Si2Sr | 298.15 | DFT | first-principles LDA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Garay 2009_ [doi](https://doi.org/10.1016/j.jallcom.2009.05.083) | Table 2, p. 2, row 12; `ORC-D5KD6WENLG.84dafb` |  |
| -42 kJ/mol-atom | α-Si2Sr |  | DFT | first-principles LDA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Garay 2009_ [doi](https://doi.org/10.1016/j.jallcom.2009.05.083) | Table 2, p. 2, row 15; `ORC-GM7U7E26UE.427288` |  |
| -42 kJ/mol-atom | α-SrSi2 | 298.15 | DFT | first-principles LDA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009 | Table 2, p. 4, row 19; `ORC-NIY3C4KGUT.f632d2` |  |
| -35.9 kJ/mol-atom | β-SrSi2 | 298.15 | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009 | Table 2, p. 4, row 24; `ORC-GOJ3G4HACO.c6ed69` |  |
| -35.9 kJ/mol-atom | β-Si2Sr | 298.15 | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Garay 2009_ [doi](https://doi.org/10.1016/j.jallcom.2009.05.083) | Table 2, p. 2, row 11; `ORC-UDVK5MDZST.136b26` |  |
| -35.8 kJ/mol-atom | α-SrSi2 | 298.15 | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Brutti 2008_ [doi](https://doi.org/10.1016/j.jallcom.2007.03.023) | Table 2, p. 4, row 21; `ORC-4IMCOBFY5W.915b71` |  |
| -35.7 kJ/mol-atom | β-SrSi2 | 298.15 | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Brutti 2008_ [doi](https://doi.org/10.1016/j.jallcom.2007.03.023) | Table 2, p. 4, row 25; `ORC-6XYQALNSWK.8936eb` |  |
| -35.7 kJ/mol-atom | α-Si2Sr |  | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [2] Li 2011; _cites Garay 2009_ [doi](https://doi.org/10.1016/j.jallcom.2009.05.083) | Table 2, p. 2, row 14; `ORC-PPFJUUN6ZW.607caf` |  |
| -35.7 kJ/mol-atom | α-SrSi2 | 298.15 | DFT | first-principles GGA | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009 | Table 2, p. 4, row 20; `ORC-VFQ3MRKMJK.bca241` |  |
| -34.6 kJ/mol-atom | α-SrSi2 | 298.15 | unspecified |  | [Si–Sr](https://data.orchid-project.org/systems/SI-SR.html) | [1] Garay 2009; _cites Imai 2002_ [doi](https://doi.org/10.1016/s0966-9795%2802%2900003-1) | Table 2, p. 4, row 18; `ORC-AQJY7ADXBD.b51260` |  |

### 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 Si2Sr

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -42.7 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -42.7 | kJ/mol-atom | 4.3 | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 4.3 |
| -40.3 | kJ/mol-atom | 3.7 | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.7 |
| -40.3 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -67.3 | kJ/mol-atom |  | 0.05 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -44.7 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -44.7 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -42 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -42 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.9 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.9 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.8 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.7 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.7 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -35.7 | kJ/mol-atom |  | 0.05 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -34.6 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |

## 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 Si2Sr

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaaaacol | -30.715 | -0.318344 | I4_1/amd | 0 | 0 | no |
| OQMD | oqmd-6867 | -35.357 | -0.366453 | I41/amd | 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. Andres Garay, Gerardo Trápaga, Zi-Kui Liu, Raymundo Arróyave, Thermodynamic modeling of the Si–Sr system, Calphad 33, 550-556 (2009). [doi:10.1016/j.calphad.2009.07.001](https://doi.org/10.1016/j.calphad.2009.07.001)
2. Kai Li, Shuhong Liu, Chunsheng Sha, Yong Du, A thermodynamic reassessment of the Si–Sr system, Calphad 35, 594-600 (2011). [doi:10.1016/j.calphad.2011.09.007](https://doi.org/10.1016/j.calphad.2011.09.007)

## 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/).