# F–Nb system

> F–Nb system: 25 accepted literature values (heat capacity / entropy / enthalpy 11, formation 11, phase transition 2, other property 1) and 0 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/F-NB.html · Markdown: https://data.orchid-project.org/systems/F-NB.md

25 accepted literature values from 1 paper(s) (experimental 1, model 16, unspecified 8); 0 calculated phase diagram(s). 28 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/F-NB.json) · [CSV](https://data.orchid-project.org/systems/F-NB.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#F-NB) · [phases (9)](https://data.orchid-project.org/phases/pages/F-NB.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/F-NB.html) · [Markdown](https://data.orchid-project.org/systems/F-NB.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 1 |
| model | 16 |
| unspecified | 8 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| phase transition | 2 |
| formation | 11 |
| heat capacity / entropy / enthalpy | 11 |
| other property | 1 |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/F/F-NB.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/F/F-NB.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, F–Nb system (11)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| Nb2F10(g) |  | -294.263 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 6; `ORC-ZSMYDT6LEW.2d0fd8` |  |
| Nb3F15(g) |  | -296.38 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 7; `ORC-5FDDV435DD.850cf0` |  |
| NbF(g) |  | 117.88 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 1; `ORC-CLYRTLS66S.3ecef6` |  |
| NbF2(g) |  | -112.887 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 2; `ORC-ZVWDFNQA6L.737c44` |  |
| NbF3 (cr) | [NbF3](https://data.orchid-project.org/compounds/NbF3.html) | -294.228 kJ/mol-atom | 298.15 | unspecified | -283.574 (mp-aaaaacrb) | -279.161 (oqmd-11298) | [1] Capelli 2018 | Table 1, p. 3, row 1; `ORC-IQHZQM7MW3.8ab981` |  |
| NbF3(g) |  | -201.102 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 3; `ORC-WUROX2PQVN.025e93` |  |
| NbF4 (cr) | [NbF4](https://data.orchid-project.org/compounds/NbF4.html) | -303.534 kJ/mol-atom | 298.15 | unspecified | -307.535 (mp-aaaaaccm) | -301.623 (oqmd-4482) | [1] Capelli 2018 | Table 1, p. 3, row 3; `ORC-7UHF2ZCB75.cc67c7` |  |
| NbF4(g) |  | -259.292 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 4; `ORC-2WQUWRMXXV.9e2da1` |  |
| NbF5 (cr) | [NbF5](https://data.orchid-project.org/compounds/NbF5.html) | -302.293 kJ/mol-atom | 298.15 | unspecified | -323.687 (mp-aaaabbqt) | -314.07 (oqmd-5080) | [1] Capelli 2018 | Table 1, p. 3, row 5; `ORC-K6AKSHJ42X.2b9893` |  |
| NbF5 (liq) |  | -299.917 kJ/mol-atom | 298.15 | unspecified |  |  | [1] Capelli 2018 | Table 1, p. 3, row 6; `ORC-P3ECFLP6FF.28ca3c` |  |
| NbF5(g) |  | -286.708 kJ/mol-atom | 298.15 | model |  |  | [1] Capelli 2018 | Table 7, p. 6, row 5; `ORC-EN4I7UQFNU.9d25c8` |  |

## Other properties

### Phase transition (2)

Table: Phase transition, F–Nb system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 573 K | 573 | other: NbF4 disproportionation (P ≃ 6.6 · 10^-4 bar); _alloy: Nb 0.2_ | model | [1] Capelli 2018 | Table 8, p. 6, row 4; `ORC-2ZH2VKNNS7` |  |
| Phase transition | 573 K | 573 | other: NbF4 disproportionation (P ≃ 6.6 · 10^-4 bar); _alloy: Nb 0.2_ | model | [1] Capelli 2018; _cites Gortsema 1965_ [doi](https://doi.org/10.1021/ic50024a012) | Table 8, p. 6, row 3; `ORC-4THHDAUPLM` |  |

### Heat capacity / entropy / enthalpy (11)

Table: Heat capacity / entropy / enthalpy, F–Nb system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy; _printed: S0(298)_ | 44.5767 J/mol-atom/K | 298.15 | Nb2F10(g); _alloy: Nb 0.166667_ | model | [1] Capelli 2018 | Table 7, p. 6, row 6; `ORC-ZSMYDT6LEW.9d1e34` |  |
| Entropy; _printed: S0(298)_ | 40.6472 J/mol-atom/K | 298.15 | Nb3F15(g); _alloy: Nb 0.166667_ | model | [1] Capelli 2018 | Table 7, p. 6, row 7; `ORC-5FDDV435DD.c70c15` |  |
| Entropy; _printed: S0(298)_ | 119.93 J/mol-atom/K | 298.15 | NbF(g); _alloy: Nb 0.5_ | model | [1] Capelli 2018 | Table 7, p. 6, row 1; `ORC-CLYRTLS66S.152174` |  |
| Entropy; _printed: S0(298)_ | 94.9033 J/mol-atom/K | 298.15 | NbF2(g); _alloy: Nb 0.333333_ | model | [1] Capelli 2018 | Table 7, p. 6, row 2; `ORC-ZVWDFNQA6L.51465f` |  |
| Entropy; _printed: S0(298)_ | 27.685 J/mol-atom/K | 298.15 | NbF3 (cr); _alloy: Nb 0.25_ | unspecified | [1] Capelli 2018 | Table 1, p. 3, row 1; `ORC-IQHZQM7MW3.368d08` |  |
| Entropy; _printed: S0(298)_ | 75.0625 J/mol-atom/K | 298.15 | NbF3(g); _alloy: Nb 0.25_ | model | [1] Capelli 2018 | Table 7, p. 6, row 3; `ORC-WUROX2PQVN.7d8d9a` |  |
| Entropy; _printed: S0(298)_ | 27.098 J/mol-atom/K | 298.15 | NbF4 (cr); _alloy: Nb 0.2_ | unspecified | [1] Capelli 2018 | Table 1, p. 3, row 3; `ORC-7UHF2ZCB75.ee676d` |  |
| Entropy; _printed: S0(298)_ | 66.352 J/mol-atom/K | 298.15 | NbF4(g); _alloy: Nb 0.2_ | model | [1] Capelli 2018 | Table 7, p. 6, row 4; `ORC-2WQUWRMXXV.9e04fb` |  |
| Entropy; _printed: S0(298)_ | 26.7083 J/mol-atom/K | 298.15 | NbF5 (cr); _alloy: Nb 0.166667_ | unspecified | [1] Capelli 2018 | Table 1, p. 3, row 5; `ORC-K6AKSHJ42X.707f9b` |  |
| Entropy; _printed: S0(298)_ | 33.4383 J/mol-atom/K | 298.15 | NbF5 (liq); _alloy: Nb 0.166667_ | unspecified | [1] Capelli 2018 | Table 1, p. 3, row 6; `ORC-P3ECFLP6FF.2487f7` |  |
| Entropy; _printed: S0(298)_ | 57.81 J/mol-atom/K | 298.15 | NbF5(g); _alloy: Nb 0.166667_ | model | [1] Capelli 2018 | Table 7, p. 6, row 5; `ORC-EN4I7UQFNU.6c0fe0` |  |

### Other property (1)

Table: Other property, F–Nb system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Other; _printed: ΔfusH_ | 12.22 unspecified ± 0.06 | 348.6 |  | experimental | [1] Capelli 2018; _cites Brady 1960_ [doi](https://doi.org/10.1021/j100834a018) | p. 2; `ORC-ERWZ72VUPS` | “From their data, the standard entropy of formation S0(NbF5, cr, 298 K) = 160.25 ± 3 J K-1 mol-1 and the enthalpy of fusion ΔfusH = 12.22 ± 0.06 kJ mol-1 at Tfus = 348.6 K were also derived.” |

## Sources

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

1. E. Capelli, R.J.M. Konings, Thermodynamic assessment of the niobium-fluorine system by coupling density functional theory and CALPHAD approach, Journal of Fluorine Chemistry 208, 55-64 (2018). [doi:10.1016/j.jfluchem.2018.01.011](https://doi.org/10.1016/j.jfluchem.2018.01.011)

## 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/).