S–Se phases

6 phases (tier A 2, liquid 1, gas 1, needs_review 2); 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 · full JSON · S–Se system page · Markdown · field reference

Phases of the S–Se system (6)
Phase	Structure	Basis	Stability (calculated)	TDB models
ORTHORHOMBIC_A16 phase:s-se:a16-orthorhombic	alpha-S · A16 · oF128 · Fddd (70)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–384.34 K, x(Se) 0–0.15751	1
HEXAGONAL_A8 phase:s-se:a8-hexagonal	gamma-Se · A8 · hP3 · P3_121 (152)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–494 K, x(Se) 0.90441–1	1
GAS phase:s-se:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 735.04–2500 K, x(Se) 0–1	1
LIQUID phase:s-se:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 356.72–1040 K, x(Se) 0–1	1
MONOCLINIC_S phase:s-se:s-monoclinic		needs_review	not stable in 1 calculated diagram(s)	1
SSE phase:s-se:sse		needs_review	stable in 1 of 1 calculated diagram(s): 300–433.11 K, x(Se) 0.34802–0.83282	1

ORTHORHOMBIC_A16 (S–Se)

Id: phase:s-se:a16-orthorhombic; status assigned
Structure: alpha-S · A16 · oF128 · Fddd (70); type st:a16-alpha-s-of128; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–384.34 K, x(Se) 0–0.15751
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:a16-orthorhombic
tdb: tdb:SSe-17Gua.tdb:ORTHORHOMBIC_A16

TDB models of ORTHORHOMBIC_A16 (1): PHASE and CONSTITUENT statements as written

SSe-17Gua.tdb: ORTHORHOMBIC_A16, type code %, sha256 69fc3205ab133df2…

49: PHASE ORTHORHOMBIC_A16 % 1 1 !
50: CONST ORTHORHOMBIC_A16 : S% SE : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (2017).
assessment that models this phase

HEXAGONAL_A8 (S–Se)

Id: phase:s-se:a8-hexagonal; status assigned
Structure: gamma-Se · A8 · hP3 · P3_121 (152); type st:a8-gamma-se-hp3; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–494 K, x(Se) 0.90441–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:a8-hexagonal
tdb: tdb:SSe-17Gua.tdb:HEXAGONAL_A8

TDB models of HEXAGONAL_A8 (1): PHASE and CONSTITUENT statements as written

SSe-17Gua.tdb: HEXAGONAL_A8, type code %, sha256 69fc3205ab133df2…

44: PHASE HEXAGONAL_A8 % 1 1 !
45: CONST HEXAGONAL_A8 : S SE% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (2017).
assessment that models this phase

GAS (S–Se)

Id: phase:s-se:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 735.04–2500 K, x(Se) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:gas
tdb: tdb:SSe-17Gua.tdb:GAS

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

SSe-17Gua.tdb: GAS, type code %, sha256 69fc3205ab133df2…

62: PHASE GAS:G % 1 1 !
63: CONST GAS:G : S S2 S3 S4 S5 S6 S7 S8 SSE SE SE2 SE3 SE4 SE5 SE6 SE7 SE8 : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (2017).
assessment that models this phase

LIQUID (S–Se)

Id: phase:s-se:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 356.72–1040 K, x(Se) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:liquid
tdb: tdb:SSe-17Gua.tdb:LIQUID

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

SSe-17Gua.tdb: LIQUID, type code %, sha256 69fc3205ab133df2…

39: PHASE LIQUID:L % 1 1 !
40: CONST LIQUID:L : S SE : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (2017).
assessment that models this phase

MONOCLINIC_S (S–Se)

Id: phase:s-se:s-monoclinic; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:MONOCLINIC; no_structure_token
Candidate (sgte_mmc2): beta-S · mP48 · P2_1/c (14) — Hallstedt 2025 mmc2 row for MONOCLINIC_S: beta-S
Candidate (tdb_comment): beta-S · mP48 · P2_1/a — SSe-17Gua.tdb: 'Prototype beta-S (mP48, P2_1/a)'
Stability: not stable in 1 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:s-monoclinic
tdb: tdb:SSe-17Gua.tdb:MONOCLINIC_S

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

SSe-17Gua.tdb: MONOCLINIC_S, type code %, sha256 69fc3205ab133df2…

54: PHASE MONOCLINIC_S % 1 1 !
55: CONST MONOCLINIC_S : S% SE : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (2017).
assessment that models this phase

SSE (S–Se)

Id: phase:s-se:sse; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model; sgte_mmc2_row_incomplete
Candidate (sgte_mmc2): (SSe) — Hallstedt 2025 mmc2 row for SSE: SSe (X-phase)
Stability: stable in 1 of 1 calculated diagram(s): 300–433.11 K, x(Se) 0.34802–0.83282
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:s-se:sse
tdb: tdb:SSe-17Gua.tdb:SSE

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

SSe-17Gua.tdb: SSE, type code %, sha256 69fc3205ab133df2…

59: PHASE SSE % 1 1 !
60: CONST SSE : S SE : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2016.10.037 Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu, First-principles calculations and thermodynamic modeling of the S-Se system and implications for chalcogenide alloys, Journal of Alloys and Compounds 694, 510-521 (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). doi: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). doi: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.

@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}
}