# Al–Np phases

> Al–Np system: 8 phases (tier A 7, liquid 1); 7 stable in a calculated diagram in the ORCHID phase registry, with names, structure type when the stored evidence supports an assignment under the stated tier rules, calculated stability, verbatim TDB PHASE/CONSTITUENT statements and example references.

HTML: https://data.orchid-project.org/phases/pages/AL-NP.html · Markdown: https://data.orchid-project.org/phases/pages/AL-NP.md

8 phases (tier A 7, liquid 1); 7 stable in a calculated diagram. Structure types are assigned only when the stored evidence supports an assignment under the stated tier rules (tier A: standard phase name; tier B: unique Materials Project + OQMD on-hull match, DFT-supported; tier C: one structure stated by the assessment's crystallographic table, assessor-stated); other phases list candidates and are marked needs_review. Stability is from phase diagrams calculated with pycalphad from the SGTE binary collection (evidence class: model).

Data: [interactive registry](https://orchid-project.org/phases/?q=AL-NP) · [full JSON](https://data.orchid-project.org/phases/systems/AL-NP.json) · [Al–Np system page](https://data.orchid-project.org/systems/AL-NP.html) · [Markdown](https://data.orchid-project.org/phases/pages/AL-NP.md) · [field reference](https://data.orchid-project.org/phases/SCHEMA.md)

Table: Phases of the Al–Np system (8)

| Phase | Structure | Basis | Stability (calculated) | Literature values | TDB models |
|---|---|---|---|---:|---:|
| [AL2NP_C15](#phase-al-np-al2np-c15); _phase:al-np:al2np-c15_ | Cu2Mg · C15 · cF24 · Fd-3m (227) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–1849.41 K, x(Np) 0.33333–0.33333 | 0 | 1 |
| [AL3NP_L12](#phase-al-np-al3np-l12); _phase:al-np:al3np-l12_ | AuCu3 · L1_2 · cP4 · Pm-3m (221) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–1610 K, x(Np) 0.25–0.25 | 0 | 1 |
| [AL4NP_D1B](#phase-al-np-al4np-d1b); _phase:al-np:al4np-d1b_ | Al4U · D1_b · oI20 · Imma (74) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–1085.08 K, x(Np) 0.2–0.2 | 0 | 1 |
| [BCC_A2](#phase-al-np-bcc-a2); _phase:al-np:bcc-a2_ | W · A2 · cI2 · Im-3m (229) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 654.68–917.21 K, x(Np) 0.99824–1 | 0 | 1 |
| [FCC_A1](#phase-al-np-fcc-a1); _phase:al-np:fcc-a1_ | Cu · A1 · cF4 · Fm-3m (225) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–933.47 K, x(Np) 0–0 | 0 | 1 |
| [HCP_A3](#phase-al-np-hcp-a3); _phase:al-np:hcp-a3_ | Mg · A3 · hP2 · P6_3/mmc (194) | tier A: standard phase name | not stable in 1 calculated diagram(s) | 0 | 1 |
| [LIQUID](#phase-al-np-liquid); _phase:al-np:liquid_ | liquid | liquid | stable in 1 of 1 calculated diagram(s): 916.84–2500 K, x(Np) 0–1 | 0 | 1 |
| [ORTHO_AC](#phase-al-np-ortho-ac); _phase:al-np:ortho-ac_ | alpha-Np · A_c · oP8 · Pnma (62) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–654.68 K, x(Np) 1–1 | 0 | 1 |

## AL2NP_C15 (Al–Np)

- Id: `phase:al-np:al2np-c15`; status `assigned`
- Structure: Cu2Mg · C15 · cF24 · Fd-3m (227); type `st:c15-cu2mg-cf24`; tier A: standard phase name; confidence high
- Stoichiometry: Al 0.6667, Np 0.3333
- Stability: stable in 1 of 1 calculated diagram(s): 300–1849.41 K, x(Np) 0.33333–0.33333
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:al2np-c15)

Names (2): _corpus: _corpus:phase:al-np:al2np-c15  
_tdb: _tdb:AlNp-10Sed.tdb:AL2NP_C15  


### TDB models of AL2NP_C15 (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): AL2NP_C15, type code %, sha256 `34943cc0a95229e5…`

~~~~text
63: PHASE AL2NP_C15 % 2 2 1 !
64: CONST AL2NP_C15 : AL : NP : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## AL3NP_L12 (Al–Np)

- Id: `phase:al-np:al3np-l12`; status `assigned`
- Structure: AuCu3 · L1_2 · cP4 · Pm-3m (221); type `st:l1-2-aucu3-cp4`; tier A: standard phase name; confidence high
- Stoichiometry: Al 0.7500, Np 0.2500
- Stability: stable in 1 of 1 calculated diagram(s): 300–1610 K, x(Np) 0.25–0.25
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:al3np-l12)

Names (2): _corpus: _corpus:phase:al-np:al3np-l12  
_tdb: _tdb:AlNp-10Sed.tdb:AL3NP_L12  


### TDB models of AL3NP_L12 (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): AL3NP_L12, type code %, sha256 `34943cc0a95229e5…`

~~~~text
58: PHASE AL3NP_L12 % 2 3 1 !
59: CONST AL3NP_L12 : AL : NP : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## AL4NP_D1B (Al–Np)

- Id: `phase:al-np:al4np-d1b`; status `assigned`
- Structure: Al4U · D1_b · oI20 · Imma (74); type `st:d1-b-al4u-oi20`; tier A: standard phase name; confidence high
- Caveat: DFT agrees: on-hull mp-aaaaaylk and oqmd-20884, space group 74
- Stoichiometry: Al 0.8000, Np 0.2000
- Stability: stable in 1 of 1 calculated diagram(s): 300–1085.08 K, x(Np) 0.2–0.2
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:al4np-d1b)

Names (4): _corpus: _corpus:phase:al-np:al4np-d1b  
_mp: _mp:mp-aaaaaylk  
_oqmd: _oqmd:oqmd-20884  
_tdb: _tdb:AlNp-10Sed.tdb:AL4NP_D1B  


### TDB models of AL4NP_D1B (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): AL4NP_D1B, type code %, sha256 `34943cc0a95229e5…`

~~~~text
53: PHASE AL4NP_D1B % 2 4 1 !
54: CONST AL4NP_D1B : AL : NP : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## BCC_A2 (Al–Np)

- Id: `phase:al-np:bcc-a2`; status `assigned`
- Structure: W · A2 · cI2 · Im-3m (229); type `st:a2-w-ci2`; tier A: standard phase name; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 654.68–917.21 K, x(Np) 0.99824–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:bcc-a2)

Names (2): _corpus: _corpus:phase:al-np:bcc-a2  
_tdb: _tdb:AlNp-10Sed.tdb:BCC_A2  


### TDB models of BCC_A2 (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): BCC_A2, type code %B, sha256 `34943cc0a95229e5…`

~~~~text
38: PHASE BCC_A2 %B 2 1 3 !
39: CONST BCC_A2 : AL NP% : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## FCC_A1 (Al–Np)

- Id: `phase:al-np:fcc-a1`; status `assigned`
- Structure: Cu · A1 · cF4 · Fm-3m (225); type `st:a1-cu-cf4`; tier A: standard phase name; confidence high
- Stoichiometry: Al 1.0000
- Stability: stable in 1 of 1 calculated diagram(s): 300–933.47 K, x(Np) 0–0
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:fcc-a1)

Names (2): _corpus: _corpus:phase:al-np:fcc-a1  
_tdb: _tdb:AlNp-10Sed.tdb:FCC_A1  


### TDB models of FCC_A1 (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): FCC_A1, type code %A, sha256 `34943cc0a95229e5…`

~~~~text
33: PHASE FCC_A1 %A 2 1 1 !
34: CONST FCC_A1 : AL : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## HCP_A3 (Al–Np)

- Id: `phase:al-np:hcp-a3`; status `assigned`
- Structure: Mg · A3 · hP2 · P6_3/mmc (194); type `st:a3-mg-hp2`; tier A: standard phase name; confidence high
- Stoichiometry: Al 1.0000
- Stability: not stable in 1 calculated diagram(s)
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:hcp-a3)

Names (2): _corpus: _corpus:phase:al-np:hcp-a3  
_tdb: _tdb:AlNp-10Sed.tdb:HCP_A3  


### TDB models of HCP_A3 (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): HCP_A3, type code %A, sha256 `34943cc0a95229e5…`

~~~~text
43: PHASE HCP_A3 %A 2 1 0.5 !
44: CONST HCP_A3 : AL : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## LIQUID (Al–Np)

- Id: `phase:al-np:liquid`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 916.84–2500 K, x(Np) 0–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:liquid)

Names (2): _corpus: _corpus:phase:al-np:liquid  
_tdb: _tdb:AlNp-10Sed.tdb:LIQUID  


### TDB models of LIQUID (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): LIQUID, type code %, sha256 `34943cc0a95229e5…`

~~~~text
28: PHASE LIQUID:L % 1 1 !
29: CONST LIQUID:L : AL AL2NP NP : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## ORTHO_AC (Al–Np)

- Id: `phase:al-np:ortho-ac`; status `assigned`
- Structure: alpha-Np · A_c · oP8 · Pnma (62); type `st:a-c-alpha-np-op8`; tier A: standard phase name; confidence high
- Stoichiometry: Np 1.0000
- Stability: stable in 1 of 1 calculated diagram(s): 300–654.68 K, x(Np) 1–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:al-np:ortho-ac)

Names (2): _corpus: _corpus:phase:al-np:ortho-ac  
_tdb: _tdb:AlNp-10Sed.tdb:ORTHO_AC  


### TDB models of ORTHO_AC (1): PHASE and CONSTITUENT statements as written

[AlNp-10Sed.tdb](https://orchid-project.org/data/databases/sgte-binary/AlNp-10Sed.tdb): ORTHO_AC, type code %, sha256 `34943cc0a95229e5…`

~~~~text
48: PHASE ORTHO_AC % 1 1 !
49: CONST ORTHO_AC : NP : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.jnucmat.2009.11.023](https://doi.org/10.1016/j.jnucmat.2009.11.023) D. Sedmidubský, R.J.M. Konings, P. Souček, Ab-initio calculations and phase diagram assessments of An–Al systems (An= U, Np, Pu), Journal of Nuclear Materials 397, 1-7 (2010).  
_assessment that models this phase_

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Registry: phase registry of binary systems (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735970
- 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 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); the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work).

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_phase_registry_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Registry: phase registry of binary systems}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735970},
  url       = {https://doi.org/10.5281/zenodo.23735970},
  note      = {Version 1, machine-extracted}
}

@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 the ORCHID phase registry and the sources named on the page (TDB assessments, Hallstedt 2025, Materials Project, OQMD). TDB statements are quoted as written; parameter expressions are not reproduced. Field reference: [SCHEMA.md](https://data.orchid-project.org/phases/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt).