# Nd–O system > Nd–O system: 19 accepted literature values (phase transition 14, crystal structure 3, formation 1, heat capacity / entropy / enthalpy 1) and 2 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote. HTML: https://data.orchid-project.org/systems/ND-O.html · Markdown: https://data.orchid-project.org/systems/ND-O.md 19 accepted literature values from 1 paper(s) (experimental 12, model 7); 2 calculated phase diagram(s). Data: [JSON](https://data.orchid-project.org/literature/systems/ND-O.json) · [CSV](https://data.orchid-project.org/systems/ND-O.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#ND-O) · [interactive phase diagram](https://orchid-project.org/phase-diagrams/#ND-O/NdO-07Zin.json) · [phases (10)](https://data.orchid-project.org/phases/pages/ND-O.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/ND-O.html) · [Markdown](https://data.orchid-project.org/systems/ND-O.md) Table: Accepted values by evidence class | Evidence class | Values | |---|---:| | experimental | 12 | | model | 7 | Table: Accepted values by property group | Property group | Values | |---|---:| | phase transition | 14 | | formation | 1 | | heat capacity / entropy / enthalpy | 1 | | crystal structure | 3 | ## 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 | |---|---|---|---| | NdO-07Zin.tdb | M. Zinkevich, Prog. Mater. Sci., 52, 597-647(2007). [doi:10.1016/j.pmatsci.2006.09.002](https://doi.org/10.1016/j.pmatsci.2006.09.002) | `0671e946c589d9b94db9de71b22e6f955c5c0d3ee76a1f9156ef1065d6e044da` | [viewer](https://orchid-project.org/phase-diagrams/#ND-O/NdO-07Zin.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/NdO-07Zin.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/NdO-07Zin.json) | | NdO-15Dot.tdb | G. Dottavio, Y. Pontillon, L. Desgranges, C. Gueneau, R.C. Belin, J. Nucl. Mater., 458, 394-405(2015). [doi:10.1016/j.jnucmat.2014.12.061](https://doi.org/10.1016/j.jnucmat.2014.12.061) | `cbc54824da87bc68adb0c2ab2e9bdbffffff54a065ce55885a75736f27ead472` | [viewer](https://orchid-project.org/phase-diagrams/#ND-O/NdO-15Dot.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/NdO-15Dot.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/NdO-15Dot.json) | Table: Calculated three-phase invariants (model, mole fraction of the second component) | TDB file | T (K) | Phases at the invariant | |---|---:|---| | NdO-15Dot.tdb | 1305.26 | ION (x(O) 0.00973) + BCC_A2 (x(O) 0.01477) + A_R2O3_D52 (x(O) 0.6) | Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/ND/ND-O.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/ND/ND-O.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, Nd–O system (1) | Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote | |---|---|---:|---:|---|---:|---:|---|---|---| | A-Nd2O3 | [Nd2O3](https://data.orchid-project.org/compounds/Nd2O3.html) | -361.38 kJ/mol-atom | 298.15 | model | -364.863 (mp-aaaaabof) | -349.317 (oqmd-30801) | [1] ZINKEVICH 2007 | Table 6.1, p. 24, row 31; `ORC-D6UKKJ6LIS.67cf27` | | ## Other properties ### Phase transition (14) Table: Phase transition, Nd–O system | Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote | |---|---:|---:|---|---|---|---|---| | Phase transition | 2333 K | 2333 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Shevtchenko 1985_ | Table 2.1, p. 6, row 37; `ORC-X55KDYELDU` | | | Phase transition | 2340 K | 2340 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Adylov 1987_ | Table 2.1, p. 6, row 41; `ORC-6QCYRKV2MC` | | | Phase transition | 2373 K | 2373 | polymorphic: A \<=> H; _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 2.2, p. 8, row 13; `ORC-IREJG4HPD3` | | | Phase transition | 2373 K | 2373 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Coutures 1976_ | Table 2.1, p. 6, row 33; `ORC-IKMN63ZS4K` | | | Phase transition | 2373 K | 2373 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Coutures 1985_ | Table 2.1, p. 6, row 39; `ORC-IONQQKPD7G` | | | Phase transition | 2373 K | 2373 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Foex 1966_ | Table 2.1, p. 6, row 31; `ORC-W7SVANOPMA` | | | Phase transition | 2373 K | 2373 | polymorphic: A ⟺ H; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Tresvyatkii 1971_ | Table 2.1, p. 6, row 35; `ORC-YZUWZEONNK` | | | Phase transition | 2435 K | 2435 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Adylov 1987_ | Table 2.1, p. 6, row 42; `ORC-PA64XTBD65` | | | Phase transition | 2453 K | 2453 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Shevtchenko 1985_ | Table 2.1, p. 6, row 38; `ORC-66QPX5PDNH` | | | Phase transition | 2473 K | 2473 | polymorphic: H \<=> X; _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 2.2, p. 8, row 27; `ORC-AXYCUBFKHE` | | | Phase transition | 2473 K | 2473 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Tresvyatkii 1971_ | Table 2.1, p. 6, row 36; `ORC-5BLKU7TSX3` | | | Phase transition | 2473 K | 2473 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Coutures 1985_ | Table 2.1, p. 6, row 40; `ORC-5SBS4NVC5V` | | | Phase transition | 2473 K | 2473 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Coutures 1976_ | Table 2.1, p. 6, row 34; `ORC-HHJRAWQ2S5` | | | Phase transition | 2473 K | 2473 | polymorphic: H ⟺ X; _alloy: Nd 0.4, O 0.6_ | experimental | [1] ZINKEVICH 2007; _cites Foex 1966_ | Table 2.1, p. 6, row 32; `ORC-OHU5CVTC4O` | | ### Heat capacity / entropy / enthalpy (1) Table: Heat capacity / entropy / enthalpy, Nd–O system | Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote | |---|---:|---:|---|---|---|---|---| | Entropy; _printed: °S_ | 157.89 unknown | 298.15 | A-Nd2O3; _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 6.1, p. 24, row 31; `ORC-D6UKKJ6LIS.cdf846` | | ### Crystal structure (3) Table: Crystal structure, Nd–O system | Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote | |---|---:|---:|---|---|---|---|---| | lattice molar volume | 45.893 cm3 mol-1 | 298.15 | Nd2O3 (A-type); _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 3.1, p. 12, row 6; `ORC-YFB3GBBEME.b7cdf9` | | | lattice molar volume | 46.796 cm3 mol-1 | 298.15 | Nd2O3 (B-type); _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 3.1, p. 12, row 6; `ORC-YFB3GBBEME.962f50` | | | lattice molar volume | 51.198 cm3 mol-1 | 298.15 | Nd2O3 (C-type); _alloy: Nd 0.4, O 0.6_ | model | [1] ZINKEVICH 2007 | Table 3.1, p. 12, row 6; `ORC-YFB3GBBEME.80a56b` | | ## Sources Reporting papers the values were read from (a value cited from another work names that work in its row). 1. M ZINKEVICH, Thermodynamics of rare earth sesquioxides, Progress in Materials Science 52, 597-647 (2007). [doi:10.1016/j.pmatsci.2006.09.002](https://doi.org/10.1016/j.pmatsci.2006.09.002) ## 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=\, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).