# As–P phases

> As–P system: 9 phases (tier A 4, liquid 1, gas 1, needs_review 3); 4 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/AS-P.html · Markdown: https://data.orchid-project.org/phases/pages/AS-P.md

9 phases (tier A 4, liquid 1, gas 1, needs_review 3); 4 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=AS-P) · [full JSON](https://data.orchid-project.org/phases/systems/AS-P.json) · [As–P system page](https://data.orchid-project.org/systems/AS-P.html) · [Markdown](https://data.orchid-project.org/phases/pages/AS-P.md) · [field reference](https://data.orchid-project.org/phases/SCHEMA.md)

Table: Phases of the As–P system (9)

| Phase | Structure | Basis | Stability (calculated) | Literature values | TDB models |
|---|---|---|---|---:|---:|
| [RHOMBOHEDRAL_A7](#phase-as-p-a7-rhombohedral); _phase:as-p:a7-rhombohedral_ | alpha-As · A7 · hR2 · R-3m (166) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–888.4 K, x(P) 0–0.07246 | 0 | 1 |
| [ASP](#phase-as-p-asp); _phase:as-p:asp_ |  | needs_review | stable in 1 of 1 calculated diagram(s): 300–832.9 K, x(P) 0.33339–0.44817 | 0 | 1 |
| [BCC_A2](#phase-as-p-bcc-a2); _phase:as-p:bcc-a2_ | W · A2 · cI2 · Im-3m (229) | tier A: standard phase name | not stable in 1 calculated diagram(s) | 0 | 1 |
| [FCC_A1](#phase-as-p-fcc-a1); _phase:as-p:fcc-a1_ | Cu · A1 · cF4 · Fm-3m (225) | tier A: standard phase name | not stable in 1 calculated diagram(s) | 0 | 1 |
| [GAS](#phase-as-p-gas); _phase:as-p:gas_ | gas | gas | stable in 1 of 1 calculated diagram(s): 704.71–2500 K, x(P) 0–1 | 0 | 1 |
| [HCP_A3](#phase-as-p-hcp-a3); _phase:as-p: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-as-p-liquid); _phase:as-p:liquid_ | liquid | liquid | not stable in 1 calculated diagram(s) | 0 | 1 |
| [RED_P](#phase-as-p-p-red); _phase:as-p:p-red_ |  | needs_review | stable in 1 of 1 calculated diagram(s): 300–732.99 K, x(P) 0.78213–1 | 0 | 1 |
| [WHITE_P](#phase-as-p-p-white); _phase:as-p:p-white_ |  | needs_review | not stable in 1 calculated diagram(s) | 0 | 1 |

## RHOMBOHEDRAL_A7 (As–P)

- Id: `phase:as-p:a7-rhombohedral`; status `assigned`
- Structure: alpha-As · A7 · hR2 · R-3m (166); type `st:a7-alpha-as-hr2`; tier A: standard phase name; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 300–888.4 K, x(P) 0–0.07246
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:as-p:a7-rhombohedral)

Names (2): _corpus: _corpus:phase:as-p:a7-rhombohedral  
_tdb: _tdb:AsP-94Ans-LB.tdb:RHOMBOHEDRAL_A7  


### TDB models of RHOMBOHEDRAL_A7 (1): PHASE and CONSTITUENT statements as written

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): RHOMBOHEDRAL_A7, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
66: PHASE RHOMBOHEDRAL_A7 % 1 1 !
67: CONST RHOMBOHEDRAL_A7 : AS% P : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## ASP (As–P)

- Id: `phase:as-p:asp`; status `needs_review`
- No structure assigned. Why: no_structure_token; off_stoichiometric_model; sgte_mmc2_row_incomplete
- Candidate (sgte_mmc2): (AsP) — Hallstedt 2025 mmc2 row for ASP: AsP
- Stability: stable in 1 of 1 calculated diagram(s): 300–832.9 K, x(P) 0.33339–0.44817
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:as-p:asp)

Names (2): _corpus: _corpus:phase:as-p:asp  
_tdb: _tdb:AsP-94Ans-LB.tdb:ASP  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): ASP, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
71: PHASE ASP % 1 1 !
72: CONST ASP : AS P : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## BCC_A2 (As–P)

- Id: `phase:as-p:bcc-a2`; status `assigned`
- Structure: W · A2 · cI2 · Im-3m (229); type `st:a2-w-ci2`; tier A: standard phase name; confidence high
- 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:as-p:bcc-a2)

Names (2): _corpus: _corpus:phase:as-p:bcc-a2  
_tdb: _tdb:AsP-94Ans-LB.tdb:BCC_A2  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): BCC_A2, type code %B, sha256 `9eaf66cd799a5abd…`

~~~~text
46: PHASE BCC_A2 %B 2 1 3 !
47: CONST BCC_A2 : AS P : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## FCC_A1 (As–P)

- Id: `phase:as-p:fcc-a1`; status `assigned`
- Structure: Cu · A1 · cF4 · Fm-3m (225); type `st:a1-cu-cf4`; tier A: standard phase name; confidence high
- 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:as-p:fcc-a1)

Names (2): _corpus: _corpus:phase:as-p:fcc-a1  
_tdb: _tdb:AsP-94Ans-LB.tdb:FCC_A1  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): FCC_A1, type code %A, sha256 `9eaf66cd799a5abd…`

~~~~text
41: PHASE FCC_A1 %A 2 1 1 !
42: CONST FCC_A1 : AS P : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## GAS (As–P)

- Id: `phase:as-p:gas`; status `assigned`
- Structure: gas; type `st:gas`; gas; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 704.71–2500 K, x(P) 0–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:as-p:gas)

Names (2): _corpus: _corpus:phase:as-p:gas  
_tdb: _tdb:AsP-94Ans-LB.tdb:GAS  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): GAS, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
74: PHASE GAS:G % 1 1 !
75: CONST GAS:G : AS AS2 AS4 ASP ASP3 AS2P2 AS3P P P2 P3 P4 : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## HCP_A3 (As–P)

- Id: `phase:as-p:hcp-a3`; status `assigned`
- Structure: Mg · A3 · hP2 · P6_3/mmc (194); type `st:a3-mg-hp2`; tier A: standard phase name; confidence high
- 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:as-p:hcp-a3)

Names (2): _corpus: _corpus:phase:as-p:hcp-a3  
_tdb: _tdb:AsP-94Ans-LB.tdb:HCP_A3  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): HCP_A3, type code %A, sha256 `9eaf66cd799a5abd…`

~~~~text
51: PHASE HCP_A3 %A 2 1 0.5 !
52: CONST HCP_A3 : AS P : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## LIQUID (As–P)

- Id: `phase:as-p:liquid`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- 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:as-p:liquid)

Names (2): _corpus: _corpus:phase:as-p:liquid  
_tdb: _tdb:AsP-94Ans-LB.tdb:LIQUID  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): LIQUID, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
36: PHASE LIQUID:L % 1 1 !
37: CONST LIQUID:L : AS P : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## RED_P (As–P)

- Id: `phase:as-p:p-red`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:RED; no_structure_token
- Candidate (dft_oqmd): P21/m (11) — on-hull OQMD As1 P5 at x(P)=0.8333
- Candidate (sgte_mmc2): (Red P) — Hallstedt 2025 mmc2 row for RED_P: Red P
- Stability: stable in 1 of 1 calculated diagram(s): 300–732.99 K, x(P) 0.78213–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:as-p:p-red)

Names (2): _corpus: _corpus:phase:as-p:p-red  
_tdb: _tdb:AsP-94Ans-LB.tdb:RED_P  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): RED_P, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
61: PHASE RED_P % 1 1 !
62: CONST RED_P : AS P% : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_assessment that models this phase_

## WHITE_P (As–P)

- Id: `phase:as-p:p-white`; status `needs_review`
- No structure assigned. Why: name_has_descriptive_tokens:WHITE; no_structure_token
- Candidate (sgte_mmc2): (White P) — Hallstedt 2025 mmc2 row for WHITE_P: White P
- Stoichiometry: P 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:as-p:p-white)

Names (2): _corpus: _corpus:phase:as-p:p-white  
_tdb: _tdb:AsP-94Ans-LB.tdb:WHITE_P  


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

[AsP-94Ans-LB.tdb](https://orchid-project.org/data/databases/sgte-binary/AsP-94Ans-LB.tdb): WHITE_P, type code %, sha256 `9eaf66cd799a5abd…`

~~~~text
56: PHASE WHITE_P % 1 1 !
57: CONST WHITE_P : P : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/0364-5916(94)90027-2](https://doi.org/10.1016/0364-5916%2894%2990027-2) I. Ansara, C. Chatillon, H.L. Lukas, T. Nishizawa, H. Ohtani, K. Ishida et al., A binary database for III–V compound semiconductor systems, Calphad 18, 177-222 (1994).  
_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).