# Nb–Zr system

> Nb–Zr system: 30 accepted literature values (crystal structure 22, formation 8) and 2 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

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

30 accepted literature values from 2 paper(s) (experimental 10, DFT 20); 2 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/NB-ZR.json) · [CSV](https://data.orchid-project.org/systems/NB-ZR.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#NB-ZR) · [interactive phase diagram](https://orchid-project.org/phase-diagrams/#NB-ZR/NbZr-19Laf.json) · [phases (7)](https://data.orchid-project.org/phases/pages/NB-ZR.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/NB-ZR.html) · [Markdown](https://data.orchid-project.org/systems/NB-ZR.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 10 |
| DFT | 20 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| formation | 8 |
| crystal structure | 22 |

## 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 |
|---|---|---|---|
| NbZr-19Laf.tdb | P. Lafaye, C. Toffolon-Masclet, J.-C. Crivello, J.-M. Joubert, Calphad, 64, 43-54(2019). [doi:10.1016/j.calphad.2018.11.002](https://doi.org/10.1016/j.calphad.2018.11.002) | `a42c533c5325c0288ad28d131e2d892bedae12ca11d5d4fdcb42b5ed2fde5084` | [viewer](https://orchid-project.org/phase-diagrams/#NB-ZR/NbZr-19Laf.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/NbZr-19Laf.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/NbZr-19Laf.json) |
| NbZr-91Fer-LB.tdb | A. Fernandez Guillermet, Z. Metallkd., 82, 478-87(1991). [doi:10.1515/ijmr-1991-820609](https://doi.org/10.1515/ijmr-1991-820609) | `7909b901df4293efe425cce3dc4eee3f1e0e2f69889b11ff43bbee64eef83ff1` | [viewer](https://orchid-project.org/phase-diagrams/#NB-ZR/NbZr-91Fer-LB.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/NbZr-91Fer-LB.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/NbZr-91Fer-LB.json) |

Table: Calculated three-phase invariants (model, mole fraction of the second component)

| TDB file | T (K) | Phases at the invariant |
|---|---:|---|
| NbZr-19Laf.tdb | 870.48 | BCC_A2 (x(Zr) 0.075) + BCC_A2#2 (x(Zr) 0.79441) + HCP_A3 (x(Zr) 0.99364) |
| NbZr-91Fer-LB.tdb | 893.02 | BCC_A2 (x(Zr) 0.07891) + BCC_A2#2 (x(Zr) 0.81288) + HCP_A3 (x(Zr) 0.99282) |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/NB/NB-ZR.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/NB/NB-ZR.json) · [CALPHAD hull NbZr-91Fer-LB](https://data.orchid-project.org/hulls/calphad-sgte/NB/NB-ZR--NbZr-91Fer-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, Nb–Zr system (8)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| C15 |  | 4.63 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 8; `ORC-6NMKXT7KYX` |  |
| C15 |  | 48.37 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 7; `ORC-2VNCHTLS4F` |  |
| C36 |  | 3.33 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 33; `ORC-YOJ22QPAHH` |  |
| C36 |  | 43.77 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 32; `ORC-THMKYKZBSM` |  |
| τ1 |  | 7.17 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 62; `ORC-NRQKQVYKZI` |  |
| τ1 |  | 41.59 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 61; `ORC-BALQKEFJT5` |  |
| τ2 |  | 1.61 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 18; `ORC-AV24NR5GS5` |  |
| τ2 |  | 41.15 kJ/mol (basis unstated) | 0 | DFT |  |  | [1] Lu 2017 | Table 2, p. 3, row 17; `ORC-ABJRSBDUF6` |  |

## Other properties

### Crystal structure (22)

Table: Crystal structure, Nb–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a; _printed: a_ | 7.85 Å | 0 | C15; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 8; `ORC-4MMNCMHWLC` |  |
| Lattice a; _printed: a_ | 8.03 Å | 0 | C15; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 7; `ORC-XQX76ZFSNI` |  |
| Lattice a; _printed: a_ | 5.7 Å | 0 | C36; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 32; `ORC-IPXCAIJM3Y.e97a2f` |  |
| Lattice a; _printed: a_ | 5.59 Å | 0 | C36; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 33; `ORC-Z6PSYAWYCB.002c59` |  |
| Lattice a; _printed: a_ | 12.76 Å | 0 | τ1; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 62; `ORC-R2ZXGIZ7AG` |  |
| Lattice a; _printed: a_ | 12.48 Å | 0 | τ1; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 61; `ORC-XI6CMDFB4J` |  |
| Lattice a; _printed: a_ | 5.68 Å | 0 | τ2; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 17; `ORC-DJ65NCPHPA.9c9487` |  |
| Lattice a; _printed: a_ | 5.59 Å | 0 | τ2; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 18; `ORC-IVVL255MFE.d28e01` |  |
| Lattice a | 3.313 not_printed ± 0.0011 | 1023.15 | α-Nb; _alloy: Nb 0.18, Zr 0.82_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 6; `ORC-HB5VGMHKXN` |  |
| Lattice a | 3.315 not_printed ± 9.000e-4 | 1023.15 | α-Nb; _alloy: Nb 0.05, Zr 0.95_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 11; `ORC-RLDF2KARFV` |  |
| Lattice a | 3.2334 not_printed ± 6.000e-4 | 1023.15 | α-Zr; _alloy: Nb 0.01, Zr 0.99_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 15; `ORC-6PZWDUZSOV.a95f08` |  |
| Lattice a | 3.2248 not_printed ± 8.000e-4 | 1023.15 | α-Zr; _alloy: Nb 0.05, Zr 0.95_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 10; `ORC-7KHDS6RIL6.36b4e2` |  |
| Lattice a | 3.3312 not_printed ± 9.000e-4 | 1073.15 | α-Nb; _alloy: Nb 0.18, Zr 0.82_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 3; `ORC-NLD76ZXANV` |  |
| Lattice a | 3.2534 not_printed ± 0.0014 | 1073.15 | α-Zr; _alloy: Nb 0.18, Zr 0.82_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 1; `ORC-RSPCJ3X3BV.101483` |  |
| Lattice a | 4.7839 not_printed ± 0.0018 | 1073.15 | δ-ZrH2-x; _alloy: Nb 0.18, Zr 0.82_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 2; `ORC-PYADIZDG2A` |  |
| Lattice c; _printed: c_ | 18.29 Å | 0 | C36; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 32; `ORC-IPXCAIJM3Y.276383` |  |
| Lattice c; _printed: c_ | 17.89 Å | 0 | C36; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 33; `ORC-Z6PSYAWYCB.2b7b7c` |  |
| Lattice c; _printed: c_ | 9.14 Å | 0 | τ2; _alloy: Nb 0.333333, Zr 0.666667_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 17; `ORC-DJ65NCPHPA.67795f` |  |
| Lattice c; _printed: c_ | 8.92 Å | 0 | τ2; _alloy: Nb 0.666667, Zr 0.333333_ | DFT | [1] Lu 2017 | Table 2, p. 3, row 18; `ORC-IVVL255MFE.ba7a76` |  |
| Lattice c | 5.15 not_printed ± 0.0017 | 1023.15 | α-Zr; _alloy: Nb 0.01, Zr 0.99_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 15; `ORC-6PZWDUZSOV.806377` |  |
| Lattice c | 5.1375 not_printed ± 0.0025 | 1023.15 | α-Zr; _alloy: Nb 0.05, Zr 0.95_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 10; `ORC-7KHDS6RIL6.c30843` |  |
| Lattice c | 5.1122 not_printed ± 0.0024 | 1073.15 | α-Zr; _alloy: Nb 0.18, Zr 0.82_ | experimental | [2] Dottor 2023 | Table 2, p. 5, row 1; `ORC-RSPCJ3X3BV.c448c4` |  |

## Sources

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

1. Hai-Jin Lu, Nan Zou, Xu-Shan Zhao, Jian-Yun Shen, Xiao-Gang Lu, Yan-Lin He, Thermodynamic investigation of the Zr-Fe-Nb system and its applications, Intermetallics 88, 91-100 (2017). [doi:10.1016/j.intermet.2017.05.008](https://doi.org/10.1016/j.intermet.2017.05.008)
2. Maxime Dottor, Jean-Claude Crivello, Jean-Marc Joubert, Critical reassessment of the H–Nb system and experimental investigation and thermodynamic modeling of the H–Nb–Zr system, Calphad 83, 102617 (2023). [doi:10.1016/j.calphad.2023.102617](https://doi.org/10.1016/j.calphad.2023.102617)

## 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/).