# Sn–Ta phases

> Sn–Ta system: 8 phases (tier A 7, liquid 1); 5 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/SN-TA.html · Markdown: https://data.orchid-project.org/phases/pages/SN-TA.md

8 phases (tier A 7, liquid 1); 5 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=SN-TA) · [full JSON](https://data.orchid-project.org/phases/systems/SN-TA.json) · [Sn–Ta system page](https://data.orchid-project.org/systems/SN-TA.html) · [Markdown](https://data.orchid-project.org/phases/pages/SN-TA.md) · [field reference](https://data.orchid-project.org/phases/SCHEMA.md)

Table: Phases of the Sn–Ta system (8)

| Phase | Structure | Basis | Stability (calculated) | Literature values | TDB models |
|---|---|---|---|---:|---:|
| [DIAMOND_A4](#phase-sn-ta-a4-diamond); _phase:sn-ta:a4-diamond_ | C (diamond) · A4 · cF8 · Fd-3m (227) | tier A: standard phase name | not stable in 1 calculated diagram(s) | 0 | 1 |
| [BCT_A5](#phase-sn-ta-a5-bct); _phase:sn-ta:a5-bct_ | beta-Sn · A5 · tI4 · I4_1/amd (141) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–505.06 K, x(Ta) 0–0 | 0 | 1 |
| [BCC_A2](#phase-sn-ta-bcc-a2); _phase:sn-ta:bcc-a2_ | W · A2 · cI2 · Im-3m (229) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–3290.21 K, x(Ta) 0.91447–1 | 0 | 1 |
| [FCC_A1](#phase-sn-ta-fcc-a1); _phase:sn-ta:fcc-a1_ | Cu · A1 · cF4 · Fm-3m (225) | tier A: standard phase name | not stable in 1 calculated diagram(s) | 0 | 1 |
| [HCP_A3](#phase-sn-ta-hcp-a3); _phase:sn-ta: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-sn-ta-liquid); _phase:sn-ta:liquid_ | liquid | liquid | stable in 1 of 1 calculated diagram(s): 505.06–4000 K, x(Ta) 0–1 | 0 | 1 |
| [SN2TA_CB](#phase-sn-ta-sn2ta-cb); _phase:sn-ta:sn2ta-cb_ | CuMg2 · C_b · oF48 · Fddd (70) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–870.21 K, x(Ta) 0.33333–0.33333 | 0 | 1 |
| [SNTA3_A15](#phase-sn-ta-snta3-a15); _phase:sn-ta:snta3-a15_ | Cr3Si · A15 · cP8 · Pm-3n (223) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–2884.81 K, x(Ta) 0.75–0.75 | 0 | 1 |

## DIAMOND_A4 (Sn–Ta)

- Id: `phase:sn-ta:a4-diamond`; status `assigned`
- Structure: C (diamond) · A4 · cF8 · Fd-3m (227); type `st:a4-c-diamond-cf8`; tier A: standard phase name; confidence high
- Stoichiometry: Sn 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:sn-ta:a4-diamond)

Names (2): _corpus: _corpus:phase:sn-ta:a4-diamond  
_tdb: _tdb:SnTa-17Mar.tdb:DIAMOND_A4  


### TDB models of DIAMOND_A4 (1): PHASE and CONSTITUENT statements as written

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): DIAMOND_A4, type code %, sha256 `4d476a22b1bb7fca…`

~~~~text
41: PHASE DIAMOND_A4 % 1 1 !
42: CONST DIAMOND_A4 : SN : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## BCT_A5 (Sn–Ta)

- Id: `phase:sn-ta:a5-bct`; status `assigned`
- Structure: beta-Sn · A5 · tI4 · I4_1/amd (141); type `st:a5-beta-sn-ti4`; tier A: standard phase name; confidence high
- Stoichiometry: Sn 1.0000
- Stability: stable in 1 of 1 calculated diagram(s): 300–505.06 K, x(Ta) 0–0
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:sn-ta:a5-bct)

Names (2): _corpus: _corpus:phase:sn-ta:a5-bct  
_tdb: _tdb:SnTa-17Mar.tdb:BCT_A5  


### TDB models of BCT_A5 (1): PHASE and CONSTITUENT statements as written

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): BCT_A5, type code %, sha256 `4d476a22b1bb7fca…`

~~~~text
46: PHASE BCT_A5 % 1 1 !
47: CONST BCT_A5 : SN : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## BCC_A2 (Sn–Ta)

- Id: `phase:sn-ta: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): 300–3290.21 K, x(Ta) 0.91447–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:sn-ta:bcc-a2)

Names (2): _corpus: _corpus:phase:sn-ta:bcc-a2  
_tdb: _tdb:SnTa-17Mar.tdb:BCC_A2  


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

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): BCC_A2, type code %B, sha256 `4d476a22b1bb7fca…`

~~~~text
31: PHASE BCC_A2 %B 2 1 3 !
32: CONST BCC_A2 : SN TA% : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## FCC_A1 (Sn–Ta)

- Id: `phase:sn-ta: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:sn-ta:fcc-a1)

Names (2): _corpus: _corpus:phase:sn-ta:fcc-a1  
_tdb: _tdb:SnTa-17Mar.tdb:FCC_A1  


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

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): FCC_A1, type code %A, sha256 `4d476a22b1bb7fca…`

~~~~text
26: PHASE FCC_A1 %A 2 1 1 !
27: CONST FCC_A1 : SN TA : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## HCP_A3 (Sn–Ta)

- Id: `phase:sn-ta: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:sn-ta:hcp-a3)

Names (2): _corpus: _corpus:phase:sn-ta:hcp-a3  
_tdb: _tdb:SnTa-17Mar.tdb:HCP_A3  


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

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): HCP_A3, type code %A, sha256 `4d476a22b1bb7fca…`

~~~~text
36: PHASE HCP_A3 %A 2 1 0.5 !
37: CONST HCP_A3 : SN TA : VA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## LIQUID (Sn–Ta)

- Id: `phase:sn-ta:liquid`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 505.06–4000 K, x(Ta) 0–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:sn-ta:liquid)

Names (2): _corpus: _corpus:phase:sn-ta:liquid  
_tdb: _tdb:SnTa-17Mar.tdb:LIQUID  


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

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): LIQUID, type code %, sha256 `4d476a22b1bb7fca…`

~~~~text
21: PHASE LIQUID:L % 1 1 !
22: CONST LIQUID:L : SN TA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## SN2TA_CB (Sn–Ta)

- Id: `phase:sn-ta:sn2ta-cb`; status `assigned`
- Structure: CuMg2 · C_b · oF48 · Fddd (70); type `st:c-b-cumg2-of48`; tier A: standard phase name; confidence high
- Caveat: DFT agrees: on-hull mp-aaabgifm and oqmd-18122, space group 70
- Stoichiometry: Sn 0.6667, Ta 0.3333
- Stability: stable in 1 of 1 calculated diagram(s): 300–870.21 K, x(Ta) 0.33333–0.33333
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:sn-ta:sn2ta-cb)

Names (4): _corpus: _corpus:phase:sn-ta:sn2ta-cb  
_mp: _mp:mp-aaabgifm  
_oqmd: _oqmd:oqmd-18122  
_tdb: _tdb:SnTa-17Mar.tdb:SN2TA_CB  


### TDB models of SN2TA_CB (1): PHASE and CONSTITUENT statements as written

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): SN2TA_CB, type code %, sha256 `4d476a22b1bb7fca…`

~~~~text
51: PHASE SN2TA_CB % 2 2 1 !
52: CONST SN2TA_CB : SN : TA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_assessment that models this phase_

## SNTA3_A15 (Sn–Ta)

- Id: `phase:sn-ta:snta3-a15`; status `assigned`
- Structure: Cr3Si · A15 · cP8 · Pm-3n (223); type `st:a15-cr3si-cp8`; tier A: standard phase name; confidence high
- Stoichiometry: Sn 0.2500, Ta 0.7500
- Stability: stable in 1 of 1 calculated diagram(s): 300–2884.81 K, x(Ta) 0.75–0.75
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:sn-ta:snta3-a15)

Names (2): _corpus: _corpus:phase:sn-ta:snta3-a15  
_tdb: _tdb:SnTa-17Mar.tdb:SNTA3_A15  


### TDB models of SNTA3_A15 (1): PHASE and CONSTITUENT statements as written

[SnTa-17Mar.tdb](https://orchid-project.org/data/databases/sgte-binary/SnTa-17Mar.tdb): SNTA3_A15, type code %, sha256 `4d476a22b1bb7fca…`

~~~~text
56: PHASE SNTA3_A15 % 2 1 3 !
57: CONST SNTA3_A15 : SN : TA : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2017.03.001](https://doi.org/10.1016/j.calphad.2017.03.001) Cassie Marker, ShunLi Shang, Xuan L. Liu, Greta Lindwall, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the Sn-Ta system, Calphad 57, 46-54 (2017).  
_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).