# Mo–Ta system

> Mo–Ta system: 25 accepted literature values (phase equilibrium 11, phase transition 9, formation 3, other property 1) and 6 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/MO-TA.html · Markdown: https://data.orchid-project.org/systems/MO-TA.md

25 accepted literature values from 3 paper(s) (experimental 20, DFT 2, unspecified 3); 6 calculated phase diagram(s). 4 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/MO-TA.json) · [CSV](https://data.orchid-project.org/systems/MO-TA.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#MO-TA) · [interactive phase diagram](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-04Xio.json) · [phases (5)](https://data.orchid-project.org/phases/pages/MO-TA.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/MO-TA.html) · [Markdown](https://data.orchid-project.org/systems/MO-TA.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 20 |
| DFT | 2 |
| unspecified | 3 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| phase transition | 9 |
| phase equilibrium | 11 |
| formation | 3 |
| crystal structure | 1 |
| other property | 1 |

## Calculated phase diagrams

Binary phase diagrams calculated with pycalphad 0.11.2 from the SGTE binary collection (Hallstedt 2025, CC BY 4.0). Evidence class: model.

Table: Assessments with a calculated phase diagram

| TDB file | Assessment | SHA-256 | Links |
|---|---|---|---|
| MoTa-04Xio.tdb | W. Xiong, Y. Du, Y. Liu, B.Y. Huang, H.H. Xu, H.L. Chen, Z. Pan, Calphad, 28, 133-40(2004). [doi:10.1016/j.calphad.2004.07.002](https://doi.org/10.1016/j.calphad.2004.07.002) | `92183b395962707869cce8b0f5f0f52504e7ad2d3f30d4fda987dad7a563dfa5` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-04Xio.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-04Xio.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-04Xio.json) |
| MoTa-05Tur.tdb | P.E.A. Turchi, V. Drchal, J. Kudrnovsky, C. Colinet, L. Kaufman, Z.-K. Liu, Phys. Rev. B, 71, 094206(2005). [doi:10.1103/PhysRevB.71.094206](https://doi.org/10.1103/PhysRevB.71.094206) | `88917f2b0afc92ac8a6a29890a28df22294c2a19f62c51bcdbd0f4d4f6986a4d` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-05Tur.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-05Tur.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-05Tur.json) |
| MoTa-20Raj.tdb | V.B. Rajkumar, Y. Du, S. Liu, K. Cheng, A.K. Srivastav, Int. J. Refract. Met. Hard Mater., 93, 105335(2020). [doi:10.1016/j.ijrmhm.2020.105335](https://doi.org/10.1016/j.ijrmhm.2020.105335) | `cfa37cba21b8d3dfb2b6d542e02f6a74a8ee75aa0c9b06a8461e27a96c423fd0` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-20Raj.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-20Raj.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-20Raj.json) |
| MoTa-22Zha.tdb | E. Zhang, Y. Tang, M. Wen, A. Obaied, I. Roslyakova, L. Zhang, Int. J. Refract. Met. Hard Mater., 103, 105780(2022). [doi:10.1016/j.ijrmhm.2022.105780](https://doi.org/10.1016/j.ijrmhm.2022.105780) | `a89e2ac4995bb46b2d14ffdec0a3b085451c33cf2b489d463e8c4c2f19782838` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-22Zha.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-22Zha.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-22Zha.json) |
| MoTa-91Kau-LB.tdb | L. Kaufman, Calphad, 15, 243-59(1991). [doi:10.1016/0364-5916(91)90004-4](https://doi.org/10.1016/0364-5916%2891%2990004-4) | `7885146f2baf656fcce5145b1929f9a2bc1ae7afb70b5a5a2ec48f4d84551d8c` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-91Kau-LB.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-91Kau-LB.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-91Kau-LB.json) |
| MoTa-99Cui.tdb | Y.W. Cui, X.G. Lu, Z.P. Jin, Metall. Mater. Trans. A, 30, 2735(1999). [doi:10.1007/s11661-999-0110-0](https://doi.org/10.1007/s11661-999-0110-0) | `1ea55690b63df718cb983c3436b519a63ebbe2ed1352444dce0c9633ccd20c66` | [viewer](https://orchid-project.org/phase-diagrams/#MO-TA/MoTa-99Cui.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/MoTa-99Cui.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/MoTa-99Cui.json) |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/MO/MO-TA.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/MO/MO-TA.json) · [CALPHAD hull MoTa-04Xio](https://data.orchid-project.org/hulls/calphad-sgte/MO/MO-TA--MoTa-04Xio.json) · [CALPHAD hull MoTa-05Tur](https://data.orchid-project.org/hulls/calphad-sgte/MO/MO-TA--MoTa-05Tur.json) · [CALPHAD hull MoTa-20Raj](https://data.orchid-project.org/hulls/calphad-sgte/MO/MO-TA--MoTa-20Raj.json) · [CALPHAD hull MoTa-91Kau-LB](https://data.orchid-project.org/hulls/calphad-sgte/MO/MO-TA--MoTa-91Kau-LB.json) · [CALPHAD hull MoTa-99Cui](https://data.orchid-project.org/hulls/calphad-sgte/MO/MO-TA--MoTa-99Cui.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, Mo–Ta system (3)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| Mo3Ta |  | 36.6 kJ/mol-atom |  | DFT |  |  | [1] Zhou 2009 | Table 6, p. 7, row 36; `ORC-KDDQUBQQJS.a6717d` |  |
| Ordered B2 TaMo |  | -26.5 kJ/mol (basis unstated) | 0 | unspecified |  |  | [2] Turchi 2005 | Table I, p. 5, row 12; `ORC-MTQBSSZCTO.5bc8c5` |  |
| Ta3Mo |  | 32.08 kJ/mol-atom |  | DFT |  |  | [1] Zhou 2009 | Table 6, p. 7, row 35; `ORC-GWWEVMKERC.e86cba` |  |

## Other properties

### Phase transition (9)

Table: Phase transition, Mo–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 3022 K | 3022 | other: No. 3, Mo-20 at.% Ta; _alloy: Mo 0.8, Ta 0.2_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 5; `ORC-T2XDEME3IU` |  |
| Phase transition | 3027 K | 3027 | other: No. 2, Mo-10 at.% Ta; _alloy: Mo 0.9, Ta 0.1_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 3; `ORC-AB3A5UXPRO` |  |
| Phase transition | 3086 K | 3086 | other: No. 5, Mo-40 at.% Ta; _alloy: Mo 0.6, Ta 0.4_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 9; `ORC-CKOZAB4O63` |  |
| Phase transition | 3119 K | 3119 | other: No. 6, Mo-50 at.% Ta; _alloy: Mo 0.5, Ta 0.5_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 11; `ORC-QL3WF2EAJO` |  |
| Phase transition | 3142 K | 3142 | other: No. 4, Mo-30 at.% Ta; _alloy: Mo 0.7, Ta 0.3_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 7; `ORC-ZIWP3XBJ5W` |  |
| Phase transition | 3172 K | 3172 | other: No. 7, Mo-60 at.% Ta; _alloy: Mo 0.4, Ta 0.6_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 13; `ORC-IMT2JEXWYH` |  |
| Phase transition | 3221 K | 3221 | other: No. 8, Mo-70 at.% Ta; _alloy: Mo 0.3, Ta 0.7_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 15; `ORC-ZIVBV7IVGV` |  |
| Phase transition | 3281 K | 3281 | other: No. 9, Mo-80 at.% Ta; _alloy: Mo 0.2, Ta 0.8_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 17; `ORC-UTVYUOEFPP` |  |
| Phase transition | 3317 K | 3317 | other: No. 10, Mo-90 at.% Ta; _alloy: Mo 0.1, Ta 0.9_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 19; `ORC-GYY25HAWOG` |  |

### Phase equilibrium (11)

Table: Phase equilibrium, Mo–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase composition |  | 2865 | other: No. 1, Mo-0 at.% Ta; _liquid: Mo 1, Ta 0_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 1; `ORC-VT6FGUOUN6` |  |
| Phase composition |  | 3047 | other: No. 2, Mo-10 at.% Ta; _liquid: Mo 0.9, Ta 0.1_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 2; `ORC-ZOO6TPNT3U` |  |
| Phase composition |  | 3056 | other: No. 3, Mo-20 at.% Ta; _liquid: Mo 0.8, Ta 0.2_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 4; `ORC-LWVOJ4HLSL` |  |
| Phase composition |  | 3092 | other: No. 5, Mo-40 at.% Ta; _liquid: Mo 0.6, Ta 0.4_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 8; `ORC-QL6KZW2ISU` |  |
| Phase composition |  | 3138 | other: No. 6, Mo-50 at.% Ta; _liquid: Mo 0.5, Ta 0.5_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 10; `ORC-PJJPAJUR72` |  |
| Phase composition |  | 3155 | other: No. 4, Mo-30 at.% Ta; _liquid: Mo 0.7, Ta 0.3_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 6; `ORC-XLNKHBZL56` |  |
| Phase composition |  | 3185 | other: No. 7, Mo-60 at.% Ta; _liquid: Mo 0.4, Ta 0.6_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 12; `ORC-ZLTV2WHQ4Y` |  |
| Phase composition |  | 3235 | other: No. 8, Mo-70 at.% Ta; _liquid: Mo 0.3, Ta 0.7_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 14; `ORC-O6XE5BIUHM` |  |
| Phase composition |  | 3272 | other: No. 11, Mo-100 at.% Ta; _liquid: Mo 0, Ta 1_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 20; `ORC-25XGTY2I6W` |  |
| Phase composition |  | 3298 | other: No. 9, Mo-80 at.% Ta; _liquid: Mo 0.2, Ta 0.8_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 16; `ORC-E2BFAPST3D` |  |
| Phase composition |  | 3337 | other: No. 10, Mo-90 at.% Ta; _liquid: Mo 0.1, Ta 0.9_ | experimental | [3] Rajkumar 2020 | Table 2, p. 5, row 18; `ORC-7RMDEHUO7V` |  |

### Crystal structure (1)

Table: Crystal structure, Mo–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| lattice unspecified axis; _printed: Lattice constant_ | 3.2139 Å |  | Ordered B2 TaMo; _alloy: Ta 0.5_ | unspecified | [2] Turchi 2005 | Table I, p. 5, row 12; `ORC-SBQQH7USJJ` |  |

### Other property (1)

Table: Other property, Mo–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| bulk modulus; _printed: Bulk modulus_ | 226.7 GPa |  | Ordered B2 TaMo; _alloy: Ta 0.5_ | unspecified | [2] Turchi 2005 | Table I, p. 5, row 12; `ORC-MTQBSSZCTO.9185ad` |  |

## Sources

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

1. S.H. Zhou, Y. Wang, L.-Q. Chen, Z.-K. Liu, R.E. Napolitano, Solution-based thermodynamic modeling of the Ni–Ta and Ni–Mo–Ta systems using first-principle calculations, Calphad 33, 631-641 (2009). [doi:10.1016/j.calphad.2009.06.006](https://doi.org/10.1016/j.calphad.2009.06.006)
2. P. E. A. Turchi, V. Drchal, J. Kudrnovský, C. Colinet, Larry Kaufman, Zi-Kui Liu, Application of\<i>ab initio\</i>and CALPHAD thermodynamics to Mo-Ta-W alloys, Phys. Rev. B 71 (2005). [doi:10.1103/physrevb.71.094206](https://doi.org/10.1103/physrevb.71.094206)
3. V.B. Rajkumar, Yong Du, Shuhong Liu, Kaiming Cheng, Ajeet Kumar Srivastav, Measurements of the melting points, liquidus, and solidus of the Mo, Ta, and Mo Ta binary alloys using a novel high-speed pyrometric technique, International Journal of Refractory Metals and Hard Materials 93, 105335 (2020). [doi:10.1016/j.ijrmhm.2020.105335](https://doi.org/10.1016/j.ijrmhm.2020.105335)

## 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-Diagrams: calculated binary phase diagrams (version 2026.10), Zenodo (2026). https://doi.org/10.5281/zenodo.23735859
- 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); 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; 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).

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_phase_diagrams_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Diagrams: calculated binary phase diagrams}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735859},
  url       = {https://doi.org/10.5281/zenodo.23735859}
}

@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/).