# Si3Ta5: enthalpy of formation

> Enthalpy of formation of Si3Ta5: 23 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/Si3Ta5.html · Markdown: https://data.orchid-project.org/compounds/Si3Ta5.md

23 accepted literature formation-enthalpy value(s) (experimental 11, model 8, DFT 1, unspecified 3); experimental median -39.7 kJ/mol-atom (n = 11); Materials Project -57.039 kJ/mol-atom (mp-aaaaacyn); OQMD -59.481 kJ/mol-atom (oqmd-3573).

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

## Literature values

Table: Enthalpy of formation of Si3Ta5 reported in the literature (23)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -54.937 kJ/mol-atom | Si0.375Ta0.625_HT | 1027 | experimental | Method unknown | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Levine 1969_ [doi](https://doi.org/10.1149/1.2411545) | Table 2, p. 2, row 19; `ORC-OVSTHRO2TO.ad70dc` |  |
| -52.423 kJ/mol-atom | Si0.375Ta0.625_HT | 1900 | experimental | Kundsen eff. method | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Myers 1957_ [doi](https://doi.org/10.1021/ja01560a007) | Table 2, p. 2, row 17; `ORC-WLRX6KX33K.5fec23` |  |
| -41.9 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | experimental | Kundsen eff. method | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Myers 1957_ [doi](https://doi.org/10.1021/ja01560a007) | Table 2, p. 2, row 15; `ORC-GCYCOHJVMK.b0dbf6` |  |
| -41.8 kJ/mol-atom ± 7.8 | Ta5Si3 (α) | 298.15 | experimental |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Myers 1957_ | Table 2, p. 6, row 50; `ORC-4J2HNEG4DB.1a0a5b` |  |
| -39.7 kJ/mol-atom | Ta5Si3 (α) | 298.15 | experimental |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Robins 1955_ [doi](https://doi.org/10.1016/0001-6160%2855%2990120-6) | Table 2, p. 6, row 53; `ORC-JBVJE5KUUC.f70741` |  |
| -39.7 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | experimental | Calorimetric method | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Robins 1955_ [doi](https://doi.org/10.1016/0001-6160%2855%2990120-6) | Table 2, p. 2, row 14; `ORC-OEWHAHTIO4.06dce4` |  |
| -38.1 kJ/mol-atom ± 1.7 | Si0.375Ta0.625_HT | 1473 | experimental | DSC | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Meschel 1998_ [doi](https://doi.org/10.1016/s0925-8388%2898%2900747-6) | Table 2, p. 2, row 12; `ORC-5O7BBL2ZS5.6cd718` |  |
| -38.1 kJ/mol-atom ± 1.7 | Ta5Si3 (α) | 298.15 | experimental |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Meschel 1998_ [doi](https://doi.org/10.1016/s0925-8388%2897%2900528-8) | Table 2, p. 6, row 51; `ORC-EUEZJLRZNK.6cc9e0` |  |
| -38.1 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | experimental | HT calorimetry | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Nowotny 1956_ [doi](https://doi.org/10.1007/bf00902640) | Table 2, p. 2, row 13; `ORC-HO7JT6JFYO.6095fb` |  |
| -37.7 kJ/mol-atom ± 4.7 | Ta5Si3 (α) | 298.15 | experimental |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Levine 1969_ [doi](https://doi.org/10.1149/1.2411545) | Table 2, p. 6, row 52; `ORC-J3HRWCLONB.545108` |  |
| -37.7 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | experimental | EMF | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Levine 1969_ [doi](https://doi.org/10.1149/1.2411545) | Table 2, p. 2, row 11; `ORC-RBNDQYDXRA.5f2d77` |  |
| -56.2 kJ/mol-atom | Ta5Si3 (α) |  | model |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Tao 2011_ | Table 2, p. 6, row 54; `ORC-OI7T2D7Y7O.2deb22` |  |
| -55 kJ/mol-atom | Si0.375Ta0.625_LT | 298.15 | model | Prediction | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites F 1988_ | Table 2, p. 2, row 9; `ORC-U5TSDHNECV.80bc75` |  |
| -52.42 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | model | Pred., Ab-in; | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Tao 2009_ [doi](https://doi.org/10.1103/physrevb.80.104103) | Table 2, p. 2, row 18; `ORC-3ANFKCW2B4.2bb240` |  |
| -52.4 kJ/mol-atom | Ta5Si3 (β) |  | model |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Tao 2011_ | Table 2, p. 6, row 57; `ORC-PTF73ZC5H2.14f247` |  |
| -52.3815 kJ/mol-atom | Si0.375Ta0.625_HT | 298.15 | model | Optimization | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013 | Table 2, p. 2, row 16; `ORC-WJ5E2FLXGU.099d9d` |  |
| -52.3807 kJ/mol-atom | Si0.375Ta0.625_LT | 298.15 | model | Optimization | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013 | Table 2, p. 2, row 8; `ORC-25XRJVWZGZ.60d870` |  |
| -52.3 kJ/mol-atom | Ta5Si3 (α) | 0 | model |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Guo 2009_ [doi](https://doi.org/10.1007/s11669-009-9579-x) | Table 2, p. 6, row 55; `ORC-RN4HQWB5IY.49c929` |  |
| -51.6 kJ/mol-atom | Ta5Si3 (β) | 0 | model |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013; _cites Guo 2009_ [doi](https://doi.org/10.1007/s11669-009-9579-x) | Table 2, p. 6, row 58; `ORC-L67DIR5REA.e05599` |  |
| -56.15 kJ/mol-atom | Si0.375Ta0.625_LT | 298.15 | DFT | Ab-initio | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [1] Drouelle 2013; _cites Tao 2009_ [doi](https://doi.org/10.1103/physrevb.80.104103) | Table 2, p. 2, row 10; `ORC-QE5SERQE3W.95bb29` |  |
| -59.8 kJ/mol-atom | Ta5Si3 (α) | 0 | unspecified |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013 | Table 2, p. 6, row 49; `ORC-DMFUOBURV7.4359f0` |  |
| -55.4 kJ/mol-atom | Ta5Si3 (β) | 0 | unspecified |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013 | Table 2, p. 6, row 56; `ORC-GKGRS2OYTE.4e030c` |  |
| -48.1 kJ/mol-atom | Ta5Si3 | 0 | unspecified |  | [Si–Ta](https://data.orchid-project.org/systems/SI-TA.html) | [2] Broz 2013 | Table 2, p. 6, row 59; `ORC-MDKPE47QNG.e6c13e` |  |

### 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 Si3Ta5

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -54.937 | kJ/mol-atom |  | 5.000e-4 | 4.1 (experimental_unspecified, cleaned_below_threshold) |  |  |  | 4.1 |
| -52.423 | kJ/mol-atom |  | 5.000e-5 | 4.2 (kems_vapour, calibrated) |  |  |  | 4.2 |
| -41.9 | kJ/mol-atom |  | 5.000e-5 | 4.2 (kems_vapour, calibrated) |  |  |  | 4.2 |
| -41.8 | kJ/mol-atom | 7.8 | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 7.8 |
| -39.7 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -39.7 | kJ/mol-atom |  | 5.000e-5 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -38.1 | kJ/mol-atom | 1.7 | 5.000e-5 | 2 (dsc_dta, prior) |  |  |  | 2 |
| -38.1 | kJ/mol-atom | 1.7 | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -38.1 | kJ/mol-atom |  | 5.000e-4 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -37.7 | kJ/mol-atom | 4.7 | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 4.7 |
| -37.7 | kJ/mol-atom |  | 5.000e-4 | 4.6 (emf, cleaned_below_threshold) |  |  |  | 4.6 |
| -56.2 | kJ/mol-atom |  | 0.05 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -55 | kJ/mol-atom |  | 5.000e-5 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -52.42 | kJ/mol-atom |  | 5.000e-5 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -52.4 | kJ/mol-atom |  | 0.05 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -52.3815 | kJ/mol-atom |  | 5.000e-8 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -52.3807 | kJ/mol-atom |  | 5.000e-8 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -52.3 | kJ/mol-atom |  | 0.05 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -51.6 | kJ/mol-atom |  | 0.05 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -56.15 | kJ/mol-atom |  | 5.000e-5 | 9.966 (dft, calibrated) |  |  |  | 9.966 |
| -59.8 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -55.4 | kJ/mol-atom |  | 0.05 | 3.5 (unknown, calibrated) |  |  |  | 3.5 |
| -48.1 | 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 Si3Ta5

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaaaacyn | -57.039 | -0.591172 | I4/mcm | 0 | 0 | no |
| OQMD | oqmd-3573 | -59.481 | -0.616476 | I4/mcm | 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. I. Drouelle, C. Servant, Thermodynamic assessment of the Si–Ta system, Journal of Alloys and Compounds 551, 293-299 (2013). [doi:10.1016/j.jallcom.2012.09.148](https://doi.org/10.1016/j.jallcom.2012.09.148)
2. P. Broz, A.U. Khan, H. Niu, X.-Q. Chen, D. Li, J. Vrestal et al., The system Ta–V–Si: Thermodynamic modeling, Journal of Solid State Chemistry 199, 171-180 (2013). [doi:10.1016/j.jssc.2012.12.003](https://doi.org/10.1016/j.jssc.2012.12.003)

## 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/).