Na–Si phases

7 phases (tier A 4, liquid 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 · Na–Si system page · Markdown · field reference

Phases of the Na–Si system (7)
Phase	Structure	Basis	Stability (calculated)	TDB models
DIAMOND_A4 phase:na-si:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2499.28 K, x(Si) 1–1	1
BCC_A2 phase:na-si:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–370.87 K, x(Si) 0–0	1
FCC_A1 phase:na-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:na-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:na-si:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 370.87–2500 K, x(Si) 0–1	1
NASI_HT phase:na-si:nasi-ht		needs_review	stable in 1 of 1 calculated diagram(s): 884.98–1071.77 K, x(Si) 0.5–0.5	1
NASI_LT phase:na-si:nasi-lt		needs_review	stable in 1 of 1 calculated diagram(s): 300–884.98 K, x(Si) 0.5–0.5	1

DIAMOND_A4 (Na–Si)

Id: phase:na-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
Stoichiometry: Si 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–2499.28 K, x(Si) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:na-si:a4-diamond
tdb: tdb:NaSi-12Hao.tdb:DIAMOND_A4

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

NaSi-12Hao.tdb: DIAMOND_A4, type code %, sha256 fded76f9bf76e977…

43: PHASE DIAMOND_A4 % 1 1 !
44: CONST DIAMOND_A4 : SI : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

BCC_A2 (Na–Si)

Id: phase:na-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: stable in 1 of 1 calculated diagram(s): 300–370.87 K, x(Si) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:na-si:bcc-a2
tdb: tdb:NaSi-12Hao.tdb:BCC_A2

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

NaSi-12Hao.tdb: BCC_A2, type code %B, sha256 fded76f9bf76e977…

33: PHASE BCC_A2 %B 2 1 3 !
34: CONST BCC_A2 : NA% SI : VA : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

FCC_A1 (Na–Si)

Id: phase:na-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:na-si:fcc-a1
tdb: tdb:NaSi-12Hao.tdb:FCC_A1

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

NaSi-12Hao.tdb: FCC_A1, type code %A, sha256 fded76f9bf76e977…

28: PHASE FCC_A1 %A 2 1 1 !
29: CONST FCC_A1 : NA SI : VA : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

HCP_A3 (Na–Si)

Id: phase:na-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:na-si:hcp-a3
tdb: tdb:NaSi-12Hao.tdb:HCP_A3

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

NaSi-12Hao.tdb: HCP_A3, type code %A, sha256 fded76f9bf76e977…

38: PHASE HCP_A3 %A 2 1 0.5 !
39: CONST HCP_A3 : NA SI : VA : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

LIQUID (Na–Si)

Id: phase:na-si:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 370.87–2500 K, x(Si) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:na-si:liquid
tdb: tdb:NaSi-12Hao.tdb:LIQUID

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

NaSi-12Hao.tdb: LIQUID, type code %, sha256 fded76f9bf76e977…

23: PHASE LIQUID:L % 1 1 !
24: CONST LIQUID:L : NA SI : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

NASI_HT (Na–Si)

Id: phase:na-si:nasi-ht; status needs_review
No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
Candidate (dft_oqmd): C2/c (15) — on-hull OQMD Na1 Si1 at x(SI)=0.5000
Candidate (sgte_mmc2): (NaSi-ht) — Hallstedt 2025 mmc2 row for NASI_HT: NaSi-ht
Stoichiometry: Na 0.5000, Si 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 884.98–1071.77 K, x(Si) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:na-si:nasi-ht
tdb: tdb:NaSi-12Hao.tdb:NASI_HT

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

NaSi-12Hao.tdb: NASI_HT, type code %, sha256 fded76f9bf76e977…

53: PHASE NASI_HT % 2 1 1 !
54: CONST NASI_HT : NA : SI : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
assessment that models this phase

NASI_LT (Na–Si)

Id: phase:na-si:nasi-lt; status needs_review
No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
Candidate (dft_oqmd): C2/c (15) — on-hull OQMD Na1 Si1 at x(SI)=0.5000
Candidate (sgte_mmc2): NaSi-lt · mC32 · C2/c (15) — Hallstedt 2025 mmc2 row for NASI_LT: NaSi-lt
Candidate (tdb_comment): NaSi-lt · mC32 · C2/c, 15 — NaSi-12Hao.tdb: 'Prototype NaSi-lt (mC32, C2/c, 15)'
Stoichiometry: Na 0.5000, Si 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–884.98 K, x(Si) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:na-si:nasi-lt
tdb: tdb:NaSi-12Hao.tdb:NASI_LT

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

NaSi-12Hao.tdb: NASI_LT, type code %, sha256 fded76f9bf76e977…

48: PHASE NASI_LT % 2 1 1 !
49: CONST NASI_LT : NA : SI : !

Example references (1 of 1; assessments first):

doi:10.2298/JMMB120113024H D. Hao, M. Bu, Y. Wang, Y. Tang, Q. Gao, M. Wang, B. Hu, Y. Du, J. Mining Metall. B, 48, 273-82(2012).
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}
}