As–Si phases

8 phases (tier A 5, tier B 1, tier C 1, 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 · full JSON · Markdown · field reference

Phases of the As–Si system (8)
Phase	Structure	Basis	Stability (calculated)	TDB models
DIAMOND_A4 phase:as-si:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1687 K, x(As) 0–0.05886	1
RHOMBOHEDRAL_A7 phase:as-si:a7-rhombohedral	alpha-As · A7 · hR2 · R-3m (166)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1090 K, x(As) 1–1	1
BCC_A2 phase:as-si:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
FCC_A1 phase:as-si:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
HCP_A3 phase:as-si:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
LIQUID phase:as-si:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1073.46–2500 K, x(As) 0–1	1
SIAS phase:as-si:sias	SiAs · mC24 · C2/m (12)	tier B: DFT-supported (unique MP + OQMD match)	stable in 1 of 1 calculated diagram(s): 300–1385.97 K, x(As) 0.5–0.5	1
SIAS2 phase:as-si:sias2	GeAs2 · oP24 · Pbam (55)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1249.77 K, x(As) 0.66667–0.66667	1

DIAMOND_A4 (As–Si)

Id: phase:as-si: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
Stability: stable in 1 of 1 calculated diagram(s): 300–1687 K, x(As) 0–0.05886
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-si:a4-diamond
tdb: tdb:SiAs-21Wu.tdb:DIAMOND_A4

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

SiAs-21Wu.tdb: DIAMOND_A4, type code %, sha256 227b4fb79ef39210…

42: PHASE DIAMOND_A4 % 1 1 !
43: CONST DIAMOND_A4 : AS SI% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

RHOMBOHEDRAL_A7 (As–Si)

Id: phase:as-si: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
Stoichiometry: As 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–1090 K, x(As) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-si:a7-rhombohedral
tdb: tdb:SiAs-21Wu.tdb:RHOMBOHEDRAL_A7

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

SiAs-21Wu.tdb: RHOMBOHEDRAL_A7, type code %, sha256 227b4fb79ef39210…

47: PHASE RHOMBOHEDRAL_A7 % 1 1 !
48: CONST RHOMBOHEDRAL_A7 : AS : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

BCC_A2 (As–Si)

Id: phase:as-si: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

Names (2): corpus: corpus:phase:as-si:bcc-a2
tdb: tdb:SiAs-21Wu.tdb:BCC_A2

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

SiAs-21Wu.tdb: BCC_A2, type code %B, sha256 227b4fb79ef39210…

32: PHASE BCC_A2 %B 2 1 3 !
33: CONST BCC_A2 : AS SI : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

FCC_A1 (As–Si)

Id: phase:as-si: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

Names (2): corpus: corpus:phase:as-si:fcc-a1
tdb: tdb:SiAs-21Wu.tdb:FCC_A1

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

SiAs-21Wu.tdb: FCC_A1, type code %A, sha256 227b4fb79ef39210…

27: PHASE FCC_A1 %A 2 1 1 !
28: CONST FCC_A1 : AS SI : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

HCP_A3 (As–Si)

Id: phase:as-si: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

Names (2): corpus: corpus:phase:as-si:hcp-a3
tdb: tdb:SiAs-21Wu.tdb:HCP_A3

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

SiAs-21Wu.tdb: HCP_A3, type code %A, sha256 227b4fb79ef39210…

37: PHASE HCP_A3 %A 2 1 0.5 !
38: CONST HCP_A3 : AS SI : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

LIQUID (As–Si)

Id: phase:as-si:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1073.46–2500 K, x(As) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-si:liquid
tdb: tdb:SiAs-21Wu.tdb:LIQUID

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

SiAs-21Wu.tdb: LIQUID, type code %, sha256 227b4fb79ef39210…

22: PHASE LIQUID:L % 1 1 !
23: CONST LIQUID:L : AS SI : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

SIAS (As–Si)

Id: phase:as-si:sias; status assigned
Structure: SiAs · mC24 · C2/m (12); type st:sias-mc24; tier B: DFT-supported (unique MP + OQMD match); confidence high
Stoichiometry: As 0.5000, Si 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–1385.97 K, x(As) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:as-si:sias
mp: mp:mp-aaaaactr
oqmd: oqmd:oqmd-8010
tdb: tdb:SiAs-21Wu.tdb:SIAS

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

SiAs-21Wu.tdb: SIAS, type code %, sha256 227b4fb79ef39210…

52: PHASE SIAS % 2 1 1 !
53: CONST SIAS : SI : AS : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
assessment that models this phase

SIAS2 (As–Si)

Id: phase:as-si:sias2; status assigned
Structure: GeAs2 · oP24 · Pbam (55); type st:geas2-op24; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (dft_space_group_55_matches_2_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: As 0.6667, Si 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1249.77 K, x(As) 0.66667–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:as-si:sias2
tdb: tdb:SiAs-21Wu.tdb:SIAS2

TDB models of SIAS2 (1): PHASE and CONSTITUENT statements as written

SiAs-21Wu.tdb: SIAS2, type code %, sha256 227b4fb79ef39210…

57: PHASE SIAS2 % 2 1 2 !
58: CONST SIAS2 : SI : AS : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2021.102296 L. Wu, Y. Du, M. Premovic, B. Hu, H. Zhang, J. Wang, Y. Liu, Calphad, 74, 102296(2021).
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}
}