# AlAs: enthalpy of formation > Enthalpy of formation of AlAs: 11 literature value(s) with sources, pages and quotes, from ORCHID. HTML: https://data.orchid-project.org/compounds/AlAs.html · Markdown: https://data.orchid-project.org/compounds/AlAs.md 11 accepted literature formation-enthalpy value(s) (experimental 8, model 2, unspecified 1). Systems: [Al–As](https://data.orchid-project.org/systems/AL-AS.html) ## Literature values Table: Enthalpy of formation of AlAs reported in the literature (11) | Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote | |---:|---|---:|---|---|---|---|---|---| | -74.1 kJ/mol (basis unstated) ± 6.5 | Al0.5As0.5(c) | 298.15 | experimental | solution calorimetry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 40_ | Table V, p. 8, row 1; `ORC-TPCHL4IPZ3.12ad36` | | | -74.1 unknown ± 6.5 | Al0.5As0.5(c) | 298.15 | experimental | solution calorimetry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 40_ | Table V, p. 8, row 1; `ORC-TPCHL4IPZ3.673b1a` | | | -60.37 kJ/mol (basis unstated) ± 0.63 | Al0.5As0.5(c) | 298.15 | experimental | Mass spectrometry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 14_ | Table V, p. 8, row 3; `ORC-IFH5NT34DE.3c3c1e` | | | -60.37 unknown ± 0.63 | Al0.5As0.5(c) | 298.15 | experimental | Mass spectrometry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 14_ | Table V, p. 8, row 3; `ORC-IFH5NT34DE.d73ff4` | | | -58.2 kJ/mol (basis unstated) ± 1.2 | Al0.5As0.5(c) | 298.15 | experimental | Sn solution calorimetry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 38_ | Table V, p. 8, row 2; `ORC-7IUYZXQGF3.1efe92` | | | -58.2 unknown ± 1.2 | Al0.5As0.5(c) | 298.15 | experimental | Sn solution calorimetry | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 38_ | Table V, p. 8, row 2; `ORC-7IUYZXQGF3.9aa222` | | | -31 kJ/mol (basis unstated) ± 3.5 | Al0.5As0.5(c) | 298.15 | experimental | Mass spectrometry and Knudsen effusion | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 41_ | Table V, p. 8, row 4; `ORC-3LBVASEB5P.33b988` | | | -31 unknown ± 3.5 | Al0.5As0.5(c) | 298.15 | experimental | Mass spectrometry and Knudsen effusion | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [1] Ansara 1984; _cites ref. 41_ | Table V, p. 8, row 4; `ORC-3LBVASEB5P.b1af7d` | | | -117.1 kJ/mol (basis unstated) | AlAs | 298.15 | model | | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [2] Onderka 2002; _cites Ansara 1994_ | Table AI, p. 18, row 47; `ORC-AGCAJ6VM5G.67b69d` | | | -117.1 kJ/mol (basis unstated) | AlAs | 298.15 | model | | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [2] Onderka 2002; _cites Kaufman 1981_ | Table AI, p. 18, row 49; `ORC-S5FUBWNL62` | | | -134.6 kJ/mol (basis unstated) | AlAs | 298.15 | unspecified | | [Al–As](https://data.orchid-project.org/systems/AL-AS.html) | [2] Onderka 2002; _cites Wagman 1968_ | Table AI, p. 18, row 48; `ORC-HOK2UWZXHL` | | ### 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 AlAs | Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective | |---:|---|---:|---:|---|---:|---:|---:|---:| | -74.1 | kJ/mol (basis unstated) | 6.5 | 0.05 | 3.2 (solution_reaction_calorimetry, calibrated) | | | | 6.5 | | -74.1 | unknown | 6.5 | 0.05 | unit 'unknown' not convertible to kJ/mol-atom | | | | 6.5 | | -60.37 | kJ/mol (basis unstated) | 0.63 | 0.005 | 4.2 (kems_vapour, calibrated) | | | | 4.2 | | -60.37 | unknown | 0.63 | 0.005 | unit 'unknown' not convertible to kJ/mol-atom | | | | 0.63 | | -58.2 | kJ/mol (basis unstated) | 1.2 | 0.05 | 3.2 (solution_reaction_calorimetry, calibrated) | | | | 3.2 | | -58.2 | unknown | 1.2 | 0.05 | unit 'unknown' not convertible to kJ/mol-atom | | | | 1.2 | | -31 | kJ/mol (basis unstated) | 3.5 | 0.5 | 4.2 (kems_vapour, calibrated) | | | | 4.2 | | -31 | unknown | 3.5 | 0.5 | unit 'unknown' not convertible to kJ/mol-atom | | | | 3.5 | | -117.1 | kJ/mol (basis unstated) | | 0.05 | 7.8 (model_calculated, calibrated) | | | | 7.8 | | -117.1 | kJ/mol (basis unstated) | | 0.05 | 7.8 (model_calculated, calibrated) | | | | 7.8 | | -134.6 | kJ/mol (basis unstated) | | 0.05 | 7 (unknown, calibrated) | | | | 7 | ## Sources 1. I. Ansara, D. Dutartre, Thermodynamic study of the Al-Ga-As-Ge system, Calphad 8, 323-342 (1984). [doi:10.1016/0364-5916(84)90035-x](https://doi.org/10.1016/0364-5916%2884%2990035-x) 2. B. Onderka, J. Unland, R. Schmid-Fetzer, Thermodynamics and phase stability in the In–N system, J. Mater. Res. 17, 3065-3083 (2002). [doi:10.1557/jmr.2002.0445](https://doi.org/10.1557/jmr.2002.0445) ## 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=\, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).