# As–Ge system

> As–Ge system: 24 accepted literature values (formation 10, crystal structure 6, phase transition 6, heat capacity / entropy / enthalpy 2) and 0 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/AS-GE.html · Markdown: https://data.orchid-project.org/systems/AS-GE.md

24 accepted literature values from 2 paper(s) (experimental 12, model 8, unspecified 4); 0 calculated phase diagram(s). 3 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: [JSON](https://data.orchid-project.org/literature/systems/AS-GE.json) · [CSV](https://data.orchid-project.org/systems/AS-GE.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#AS-GE) · [phases (8)](https://data.orchid-project.org/phases/pages/AS-GE.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/AS-GE.html) · [Markdown](https://data.orchid-project.org/systems/AS-GE.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 12 |
| model | 8 |
| unspecified | 4 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| phase transition | 6 |
| formation | 10 |
| heat capacity / entropy / enthalpy | 2 |
| crystal structure | 6 |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/AS/AS-GE.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/AS/AS-GE.json) · [CALPHAD hull GeAs-21Wu](https://data.orchid-project.org/hulls/calphad-sgte/AS/AS-GE--GeAs-21Wu.json) · [CALPHAD hull GeAs-84Ans-LB](https://data.orchid-project.org/hulls/calphad-sgte/AS/AS-GE--GeAs-84Ans-LB.json)

## Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from [dft_parity.json](https://data.orchid-project.org/literature/dft_parity.json).

Table: Enthalpies of formation, As–Ge system (10)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| GeAs | [AsGe](https://data.orchid-project.org/compounds/AsGe.html) | -5.5 kJ/mol-atom ± 2.6 | 298.15 | experimental | -4.154 (mp-aaaaaodg) | -4.148 (oqmd-15392) | [1] Chen 2022; _cites Fitzner 1996_ [doi](https://doi.org/10.1016/0925-8388%2895%2902186-8) | Table II, p. 3, row 1; `ORC-KCRVA6CSIS.5dcf56` |  |
| GeAs | [AsGe](https://data.orchid-project.org/compounds/AsGe.html) | -4.481 kJ/mol-atom | 298.15 | model | -4.154 (mp-aaaaaodg) | -4.148 (oqmd-15392) | [1] Chen 2022 | Table II, p. 3, row 5; `ORC-MF6UWYETOS.be11d3` |  |
| GeAs | [AsGe](https://data.orchid-project.org/compounds/AsGe.html) | -4.43 kJ/mol-atom | 0 | unspecified | -4.154 (mp-aaaaaodg) | -4.148 (oqmd-15392) | [1] Chen 2022 | Table II, p. 3, row 4; `ORC-MTDHJ6IIYD.792ab1` |  |
| GeAs | [AsGe](https://data.orchid-project.org/compounds/AsGe.html) | -4.14 kJ/mol-atom | 0 | model | -4.154 (mp-aaaaaodg) | -4.148 (oqmd-15392) | [1] Chen 2022; _cites Saal 2013_ | Table II, p. 3, row 2; `ORC-ABH3TKCJG4.0179ed` |  |
| GeAs | [AsGe](https://data.orchid-project.org/compounds/AsGe.html) | -2.98 kJ/mol-atom | 0 | model | -4.154 (mp-aaaaaodg) | -4.148 (oqmd-15392) | [1] Chen 2022; _cites ref. 36_ | Table II, p. 3, row 3; `ORC-CL2GG7VZYU.ceadaa` |  |
| GeAs2 | [As2Ge](https://data.orchid-project.org/compounds/As2Ge.html) | -5.8 kJ/mol-atom ± 3.2 | 298.15 | experimental | -3.963 (mp-aaaaazya) | -4.725 (oqmd-4450) | [1] Chen 2022; _cites Fitzner 1996_ [doi](https://doi.org/10.1016/0925-8388%2895%2902186-8) | Table II, p. 3, row 6; `ORC-P3DNZJPV3S.85ebc5` |  |
| GeAs2 | [As2Ge](https://data.orchid-project.org/compounds/As2Ge.html) | -5.302 kJ/mol-atom | 298.15 | model | -3.963 (mp-aaaaazya) | -4.725 (oqmd-4450) | [1] Chen 2022 | Table II, p. 3, row 10; `ORC-NGZVHTZYIS.ddb2d4` |  |
| GeAs2 | [As2Ge](https://data.orchid-project.org/compounds/As2Ge.html) | -4.78 kJ/mol-atom | 0 | unspecified | -3.963 (mp-aaaaazya) | -4.725 (oqmd-4450) | [1] Chen 2022 | Table II, p. 3, row 9; `ORC-RRIN63A2RV.5c70a4` |  |
| GeAs2 | [As2Ge](https://data.orchid-project.org/compounds/As2Ge.html) | -4.71 kJ/mol-atom | 0 | model | -3.963 (mp-aaaaazya) | -4.725 (oqmd-4450) | [1] Chen 2022; _cites Saal 2013_ | Table II, p. 3, row 7; `ORC-IZBGMMCWHM.15650e` |  |
| GeAs2 | [As2Ge](https://data.orchid-project.org/compounds/As2Ge.html) | -4.14 kJ/mol-atom | 0 | model | -3.963 (mp-aaaaazya) | -4.725 (oqmd-4450) | [1] Chen 2022; _cites ref. 36_ | Table II, p. 3, row 8; `ORC-PA4XV6U56S.6a43e1` |  |

## Other properties

### Phase transition (6)

Table: Phase transition, As–Ge system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 1021 K | 1021 | GeAs2 | experimental | [1] Chen 2022; _cites Blachnik 1971_ [doi](https://doi.org/10.1016/s0021-9614%2871%2980107-6) | p. 4; `ORC-UTXCIIIC47` | “1021 K, respectively, which is close to the results from Ugai et al.32” |
| Phase transition | 1025 K | 1025 | GeAs | experimental | [1] Chen 2022; _cites Blachnik 1971_ [doi](https://doi.org/10.1016/s0021-9614%2871%2980107-6) | p. 2; `ORC-SJUFEEEVMM` | “The results reflected that GeAs and ­GeAs2 melted at 1025 K and” |
| Phase transition | 1029 K | 1029 | GeAs2 | experimental | [1] Chen 2022; _cites Ugai 1978_ | p. 10; `ORC-OEJNUYOHFA.4080ac` | “In addition, the present results show that GeAs melts at 1037 K and  GeAs2 melts at 1032 K, which are close to 1035 K and 1029 K given by Ugai et al.32” |
| Phase transition | 1032 K | 1032 | GeAs2 | model | [1] Chen 2022 | p. 10; `ORC-OEJNUYOHFA.d9335c` | “In addition, the present results show that GeAs melts at 1037 K and  GeAs2 melts at 1032 K, which are close to 1035 K and 1029 K given by Ugai et al.32” |
| Phase transition | 1035 K | 1035 | GeAs | experimental | [1] Chen 2022; _cites Ugai 1978_ | p. 10; `ORC-OEJNUYOHFA.a44b61` | “In addition, the present results show that GeAs melts at 1037 K and  GeAs2 melts at 1032 K, which are close to 1035 K and 1029 K given by Ugai et al.32” |
| Phase transition | 1037 K | 1037 | GeAs | model | [1] Chen 2022 | p. 10; `ORC-OEJNUYOHFA.95bffd` | “In addition, the present results show that GeAs melts at 1037 K and  GeAs2 melts at 1032 K, which are close to 1035 K and 1029 K given by Ugai et al.32” |

### Heat capacity / entropy / enthalpy (2)

Table: Heat capacity / entropy / enthalpy, As–Ge system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy; _printed: °S^L - °S_ | 28.28 J/mol (basis unstated)/K | 1021 | Ge0.33As0.66; _alloy: As 0.666667, Ge 0.333333_ | unspecified | [2] Ansara 1984 | Table VI, p. 13, row 7; `ORC-UVJCEW2DLJ.3885aa` |  |
| Entropy; _printed: °S^L - °S_ | 31.22 J/mol (basis unstated)/K | 1025 | Ge0.5As0.5; _alloy: As 0.5, Ge 0.5_ | unspecified | [2] Ansara 1984 | Table VI, p. 13, row 6; `ORC-NZ7XNLZL6C.a91068` |  |

### Crystal structure (6)

Table: Crystal structure, As–Ge system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a | 15.59 Å | 298.15 | GeAs; _alloy: Ge 0.5_ | experimental | [1] Chen 2022; _cites Wadsten 1967_ [doi](https://doi.org/10.3891/acta.chem.scand.21-0593) | Table I, p. 2, row 2; `ORC-TOWQ5LIOAD.f0fb8c` |  |
| Lattice a | 14.76 Å | 298.15 | GeAs2; _alloy: Ge 0.333333_ | experimental | [1] Chen 2022; _cites Bryden 1962_ [doi](https://doi.org/10.1107/s0365110x62000407) | Table I, p. 2, row 3; `ORC-DRUM3WN564.f00b14` |  |
| Lattice b | 3.792 Å | 298.15 | GeAs; _alloy: Ge 0.5_ | experimental | [1] Chen 2022; _cites Wadsten 1967_ [doi](https://doi.org/10.3891/acta.chem.scand.21-0593) | Table I, p. 2, row 2; `ORC-TOWQ5LIOAD.ad044f` |  |
| Lattice b | 10.16 Å | 298.15 | GeAs2; _alloy: Ge 0.333333_ | experimental | [1] Chen 2022; _cites Bryden 1962_ [doi](https://doi.org/10.1107/s0365110x62000407) | Table I, p. 2, row 3; `ORC-DRUM3WN564.13dd20` |  |
| Lattice c | 9.49 Å | 298.15 | GeAs; _alloy: Ge 0.5_ | experimental | [1] Chen 2022; _cites Wadsten 1967_ [doi](https://doi.org/10.3891/acta.chem.scand.21-0593) | Table I, p. 2, row 2; `ORC-TOWQ5LIOAD.a8c100` |  |
| Lattice c | 3.728 Å | 298.15 | GeAs2; _alloy: Ge 0.333333_ | experimental | [1] Chen 2022; _cites Bryden 1962_ [doi](https://doi.org/10.1107/s0365110x62000407) | Table I, p. 2, row 3; `ORC-DRUM3WN564.af29d9` |  |

## Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

1. Shanxiong Chen, Jiong Wang, Shangzhao Yu, Biao Hu, Qing Wu, Yong Du, Thermodynamic Modeling of the Ge-X (X = As, Se, S, P) Systems, J. Electron. Mater. 51, 2114-2130 (2022). [doi:10.1007/s11664-022-09474-1](https://doi.org/10.1007/s11664-022-09474-1)
2. 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)

## 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-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). https://doi.org/10.5281/zenodo.23735891
- 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); 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_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@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/).