# H–Sr phases

> H–Sr system: 7 phases (tier A 4, liquid 1, gas 1, needs_review 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/H-SR.html · Markdown: https://data.orchid-project.org/phases/pages/H-SR.md

7 phases (tier A 4, liquid 1, gas 1, needs_review 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=H-SR) · [full JSON](https://data.orchid-project.org/phases/systems/H-SR.json) · [H–Sr system page](https://data.orchid-project.org/systems/H-SR.html) · [Markdown](https://data.orchid-project.org/phases/pages/H-SR.md) · [field reference](https://data.orchid-project.org/phases/SCHEMA.md)

Table: Phases of the H–Sr system (7)

| Phase | Structure | Basis | Stability (calculated) | Literature values | TDB models |
|---|---|---|---|---:|---:|
| [BCC_A2](#phase-h-sr-bcc-a2); _phase:h-sr:bcc-a2_ | W · A2 · cI2 · Im-3m (229) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 820–1158.5 K, x(H) 0–0.4336 | 0 | 1 |
| [FCC_A1](#phase-h-sr-fcc-a1); _phase:h-sr:fcc-a1_ | Cu · A1 · cF4 · Fm-3m (225) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–823.01 K, x(H) 0–0.05457 | 0 | 1 |
| [GAS](#phase-h-sr-gas); _phase:h-sr:gas_ | gas | gas | stable in 1 of 1 calculated diagram(s): 300–2500 K, x(H) 0–1 | 0 | 1 |
| [HCP_A3](#phase-h-sr-hcp-a3); _phase:h-sr:hcp-a3_ | Mg · A3 · hP2 · P6_3/mmc (194) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 515.1–897.96 K, x(H) 0.01676–0.21457 | 0 | 1 |
| [LIQUID](#phase-h-sr-liquid); _phase:h-sr:liquid_ | liquid | liquid | stable in 1 of 1 calculated diagram(s): 1049.06–2009.03 K, x(H) 0–0.47347 | 0 | 1 |
| [SRH2_BETA](#phase-h-sr-srh2-beta); _phase:h-sr:srh2-beta_ |  | needs_review | stable in 1 of 1 calculated diagram(s): 1129.52–1220.03 K, x(H) 0.66667–0.66667 | 1 | 1 |
| [SRH2_C37](#phase-h-sr-srh2-c37); _phase:h-sr:srh2-c37_ | Co2Si · C37 · oP12 · Pnma (62) | tier A: standard phase name | stable in 1 of 1 calculated diagram(s): 300–1129.52 K, x(H) 0.66667–0.66667 | 4 | 1 |

## BCC_A2 (H–Sr)

- Id: `phase:h-sr: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): 820–1158.5 K, x(H) 0–0.4336
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:bcc-a2)

Names (2): _corpus: _corpus:phase:h-sr:bcc-a2  
_tdb: _tdb:SrH-12Che.tdb:BCC_A2  


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

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): BCC_A2, type code %B, sha256 `57c5fa217cf9f14a…`

~~~~text
37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : SR : H VA% : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase_

## FCC_A1 (H–Sr)

- Id: `phase:h-sr:fcc-a1`; status `assigned`
- Structure: Cu · A1 · cF4 · Fm-3m (225); type `st:a1-cu-cf4`; tier A: standard phase name; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 300–823.01 K, x(H) 0–0.05457
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:fcc-a1)

Names (2): _corpus: _corpus:phase:h-sr:fcc-a1  
_tdb: _tdb:SrH-12Che.tdb:FCC_A1  


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

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): FCC_A1, type code %A, sha256 `57c5fa217cf9f14a…`

~~~~text
32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : SR : H VA% : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase_

## GAS (H–Sr)

- Id: `phase:h-sr:gas`; status `assigned`
- Structure: gas; type `st:gas`; gas; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 300–2500 K, x(H) 0–1
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:gas)

Names (2): _corpus: _corpus:phase:h-sr:gas  
_tdb: _tdb:SrH-12Che.tdb:GAS  


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

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): GAS, type code %, sha256 `57c5fa217cf9f14a…`

~~~~text
55: PHASE GAS:G % 1 1 !
56: CONST GAS:G : H H2 SR SR2 : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase_

## HCP_A3 (H–Sr)

- Id: `phase:h-sr: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: stable in 1 of 1 calculated diagram(s): 515.1–897.96 K, x(H) 0.01676–0.21457
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:hcp-a3)

Names (2): _corpus: _corpus:phase:h-sr:hcp-a3  
_tdb: _tdb:SrH-12Che.tdb:HCP_A3  


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

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): HCP_A3, type code %A, sha256 `57c5fa217cf9f14a…`

~~~~text
42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : SR : H VA% : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase_

## LIQUID (H–Sr)

- Id: `phase:h-sr:liquid`; status `assigned`
- Structure: liquid; type `st:liquid`; liquid; confidence high
- Stability: stable in 1 of 1 calculated diagram(s): 1049.06–2009.03 K, x(H) 0–0.47347
- Literature: 0 values (0 accepted) from 0 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:liquid)

Names (2): _corpus: _corpus:phase:h-sr:liquid  
_tdb: _tdb:SrH-12Che.tdb:LIQUID  


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

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): LIQUID, type code %, sha256 `57c5fa217cf9f14a…`

~~~~text
27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : H SR : !
~~~~

Example references (1 of 1; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase_

## SRH2_BETA (H–Sr)

- Id: `phase:h-sr:srh2-beta`; status `needs_review`
- No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
- Candidate (dft_mp): Pnma (62) — on-hull MP SrH2 at x(SR)=0.3333
- Candidate (dft_oqmd): Pnma (62) — on-hull OQMD H2 Sr1 at x(SR)=0.3333
- Candidate (sgte_mmc2): SrH2 — Hallstedt 2025 mmc2 row for SRH2_BETA: SrH2-beta
- Stoichiometry: H 0.6667, Sr 0.3333
- Stability: stable in 1 of 1 calculated diagram(s): 1129.52–1220.03 K, x(H) 0.66667–0.66667
- Literature: 1 values (1 accepted) from 1 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:srh2-beta)

Names (3): _corpus: _corpus:phase:h-sr:srh2-beta  
_paper: _paper:10.1016/j.calphad.2012.03.001:βSrH2  
_tdb: _tdb:SrH-12Che.tdb:SRH2_BETA  


### TDB models of SRH2_BETA (1): PHASE and CONSTITUENT statements as written

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): SRH2_BETA, type code %, sha256 `57c5fa217cf9f14a…`

~~~~text
52: PHASE SRH2_BETA % 2 1 2 !
53: CONST SRH2_BETA : SR : H : !
~~~~

Example references (2 of 2; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1016/0022-5088(80)90144-7](https://doi.org/10.1016/0022-5088%2880%2990144-7) D.T. Peterson, S.O. Nelson, Equilibrium hydrogen pressures in the strontium-hydrogen system, Journal of the Less Common Metals 72, 251-256 (1980).  
_cited as the source of values for this phase_

## SRH2_C37 (H–Sr)

- Id: `phase:h-sr:srh2-c37`; status `assigned`
- Structure: Co2Si · C37 · oP12 · Pnma (62); type `st:c37-co2si-op12`; tier A: standard phase name; confidence high
- Stoichiometry: H 0.6667, Sr 0.3333
- Stability: stable in 1 of 1 calculated diagram(s): 300–1129.52 K, x(H) 0.66667–0.66667
- Literature: 4 values (4 accepted) from 1 papers
- Interactive: [phase registry entry](https://orchid-project.org/phases/#phase:h-sr:srh2-c37)

Names (3): _corpus: _corpus:phase:h-sr:srh2-c37  
_paper: _paper:10.1016/j.calphad.2012.03.001:αSrH2  
_tdb: _tdb:SrH-12Che.tdb:SRH2_C37  


### TDB models of SRH2_C37 (1): PHASE and CONSTITUENT statements as written

[SrH-12Che.tdb](https://orchid-project.org/data/databases/sgte-binary/SrH-12Che.tdb): SRH2_C37, type code %, sha256 `57c5fa217cf9f14a…`

~~~~text
47: PHASE SRH2_C37 % 2 1 2 !
48: CONST SRH2_C37 : SR : H : !
~~~~

Example references (3 of 3; assessments first): 

- [doi:10.1016/j.calphad.2012.03.001](https://doi.org/10.1016/j.calphad.2012.03.001) Chong Chen, Man Wang, Yong Du, Qiannan Gao, Biao Hu, Shuhong Liu, Thermodynamic modeling of the Sr–X (X=H, Li, Na, Sc) systems, Calphad 38, 17-22 (2012).  
_assessment that models this phase; reports values for this phase_
- [doi:10.1002/zaac.19633240302](https://doi.org/10.1002/zaac.19633240302) P. Ehrlich, K. Peik, E. Koch, Thermochemische Messungen an den Hydridhalogeniden der Erdalkalimetalle, Zeitschrift anorg allge chemie 324, 113-128 (1963).  
_cited as the source of values for this phase_
- [doi:10.1016/0022-5088(80)90144-7](https://doi.org/10.1016/0022-5088%2880%2990144-7) D.T. Peterson, S.O. Nelson, Equilibrium hydrogen pressures in the strontium-hydrogen system, Journal of the Less Common Metals 72, 251-256 (1980).  
_cited as the source of values for 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).