Ge–O phases

10 phases (tier A 5, liquid 2, gas 2, needs_review 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 · Ge–O system page · Markdown · field reference

Phases of the Ge–O system (10)
Phase	Structure	Basis	Stability (calculated)	TDB models
DIAMOND_A4 phase:ge-o:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1211.4 K, x(O) 0–0	2
BCC_A2 phase:ge-o:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 2 calculated diagram(s)	2
FCC_A1 phase:ge-o:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 2 calculated diagram(s)	2
GAS phase:ge-o:gas	gas	gas	stable in 2 of 2 calculated diagram(s): 300–2500 K, x(O) 1–1	2
GEO2_HT phase:ge-o:geo2		needs_review	stable in 1 of 2 calculated diagram(s): 1324.19–1389.19 K, x(O) 0.66667–0.66667	2
GEO2_C4 phase:ge-o:geo2-c4	TiO2 · C4 · tP6 · P4_2/mnm (136)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–475 K, x(O) 0.66667–0.66667	2
HCP_A3 phase:ge-o:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 2 calculated diagram(s)	2
ION phase:ge-o:ion	liquid	liquid	stable in 2 of 2 calculated diagram(s): 1192.81–2500 K, x(O) 0–0.66667	2
LIQUID phase:ge-o:liquid	liquid	liquid	not stable in 2 calculated diagram(s)	2
O2GAS phase:ge-o:o2gas	gas	gas	not stable in 2 calculated diagram(s)	2

DIAMOND_A4 (Ge–O)

Id: phase:ge-o: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: Ge 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 300–1211.4 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:a4-diamond
tdb: tdb:GeO-15Din.tdb:DIAMOND_A4, tdb:GeO-21Baj-3g.tdb:DIAMOND_A4

TDB models of DIAMOND_A4 (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: DIAMOND_A4, type code %, sha256 004d6c7cf629014a…

53: PHASE DIAMOND_A4 % 1 1 !
54: CONST DIAMOND_A4 : GE : !

GeO-21Baj-3g.tdb: DIAMOND_A4, type code %, sha256 904325ae56bbb509…

55: PHASE DIAMOND_A4 % 1 1 !
56: CONST DIAMOND_A4 : GE : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

BCC_A2 (Ge–O)

Id: phase:ge-o: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 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:bcc-a2
tdb: tdb:GeO-15Din.tdb:BCC_A2, tdb:GeO-21Baj-3g.tdb:BCC_A2

TDB models of BCC_A2 (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: BCC_A2, type code %B, sha256 004d6c7cf629014a…

43: PHASE BCC_A2 %B 2 1 3 !
44: CONST BCC_A2 : GE : O VA% : !

GeO-21Baj-3g.tdb: BCC_A2, type code %B, sha256 904325ae56bbb509…

45: PHASE BCC_A2 %B 2 1 3 !
46: CONST BCC_A2 : GE : O VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

FCC_A1 (Ge–O)

Id: phase:ge-o: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 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:fcc-a1
tdb: tdb:GeO-15Din.tdb:FCC_A1, tdb:GeO-21Baj-3g.tdb:FCC_A1

TDB models of FCC_A1 (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: FCC_A1, type code %A, sha256 004d6c7cf629014a…

38: PHASE FCC_A1 %A 2 1 1 !
39: CONST FCC_A1 : GE : O VA% : !

GeO-21Baj-3g.tdb: FCC_A1, type code %A, sha256 904325ae56bbb509…

40: PHASE FCC_A1 %A 2 1 1 !
41: CONST FCC_A1 : GE : O VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

GAS (Ge–O)

Id: phase:ge-o:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–2500 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:gas
tdb: tdb:GeO-15Din.tdb:GAS, tdb:GeO-21Baj-3g.tdb:GAS

TDB models of GAS (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: GAS, type code %, sha256 004d6c7cf629014a…

69: PHASE GAS:G % 1 1 !
70: CONST GAS:G : O O2 O3 : !

GeO-21Baj-3g.tdb: GAS, type code %, sha256 904325ae56bbb509…

71: PHASE GAS:G % 1 1 !
72: CONST GAS:G : O O2 O3 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

GEO2_HT (Ge–O)

Id: phase:ge-o:geo2; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model
Candidate (tdb_comment): SiO2 · hP9 · P3_121 — GeO-15Din.tdb: 'Prototype SiO2 (hP9, P3_121), alpha-quartz'
Candidate (tdb_comment): SiO2 · hP9 · P3_121 — GeO-21Baj-3g.tdb: 'Prototype SiO2 (hP9, P3_121), alpha-quartz'
Stability: stable in 1 of 2 calculated diagram(s): 1324.19–1389.19 K, x(O) 0.66667–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:geo2
tdb: tdb:GeO-15Din.tdb:GEO2_HT, tdb:GeO-21Baj-3g.tdb:GEO2_HT

TDB models of GEO2_HT (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: GEO2_HT, type code %, sha256 004d6c7cf629014a…

63: PHASE GEO2_HT % 2 1 2 !
64: CONST GEO2_HT : GE+4 : O-2 : !

GeO-21Baj-3g.tdb: GEO2_HT, type code %, sha256 904325ae56bbb509…

65: PHASE GEO2_HT % 2 1 2 !
66: CONST GEO2_HT : GE+4 : O-2 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

GEO2_C4 (Ge–O)

Id: phase:ge-o:geo2-c4; status assigned
Structure: TiO2 · C4 · tP6 · P4_2/mnm (136); type st:c4-tio2-tp6; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–475 K, x(O) 0.66667–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:geo2-c4
tdb: tdb:GeO-15Din.tdb:GEO2_C4, tdb:GeO-21Baj-3g.tdb:GEO2_C4

TDB models of GEO2_C4 (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: GEO2_C4, type code %, sha256 004d6c7cf629014a…

58: PHASE GEO2_C4 % 2 1 2 !
59: CONST GEO2_C4 : GE+4 : O-2 : !

GeO-21Baj-3g.tdb: GEO2_C4, type code %, sha256 904325ae56bbb509…

60: PHASE GEO2_C4 % 2 1 2 !
61: CONST GEO2_C4 : GE+4 : O-2 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

HCP_A3 (Ge–O)

Id: phase:ge-o: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 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:hcp-a3
tdb: tdb:GeO-15Din.tdb:HCP_A3, tdb:GeO-21Baj-3g.tdb:HCP_A3

TDB models of HCP_A3 (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: HCP_A3, type code %, sha256 004d6c7cf629014a…

48: PHASE HCP_A3 % 2 1 0.5 !
49: CONST HCP_A3 : GE : O VA% : !

GeO-21Baj-3g.tdb: HCP_A3, type code %, sha256 904325ae56bbb509…

50: PHASE HCP_A3 % 2 1 0.5 !
51: CONST HCP_A3 : GE : O VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

ION (Ge–O)

Id: phase:ge-o:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1192.81–2500 K, x(O) 0–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:ion
tdb: tdb:GeO-15Din.tdb:ION, tdb:GeO-21Baj-3g.tdb:ION

TDB models of ION (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: ION, type code %, sha256 004d6c7cf629014a…

33: PHASE ION:Y % 2 1 1 !
34: CONST ION:Y : GE+4 : O-2 VA : !

GeO-21Baj-3g.tdb: ION, type code %, sha256 904325ae56bbb509…

35: PHASE ION:Y % 2 1 1 !
36: CONST ION:Y : GE+4 : O-2 VA : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

LIQUID (Ge–O)

Id: phase:ge-o:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stoichiometry: Ge 1.0000
Stability: not stable in 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:liquid
tdb: tdb:GeO-15Din.tdb:LIQUID, tdb:GeO-21Baj-3g.tdb:LIQUID

TDB models of LIQUID (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: LIQUID, type code %, sha256 004d6c7cf629014a…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : GE : !

GeO-21Baj-3g.tdb: LIQUID, type code %, sha256 904325ae56bbb509…

32: PHASE LIQUID:L % 1 1 !
33: CONST LIQUID:L : GE : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(2021).
assessment that models this phase

O2GAS (Ge–O)

Id: phase:ge-o:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: not stable in 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ge-o:o2gas
tdb: tdb:GeO-15Din.tdb:O2GAS, tdb:GeO-21Baj-3g.tdb:O2GAS

TDB models of O2GAS (2): PHASE and CONSTITUENT statements as written

GeO-15Din.tdb: O2GAS, type code %, sha256 004d6c7cf629014a…

66: PHASE O2GAS % 1 1 !
67: CONST O2GAS : O2 :!

GeO-21Baj-3g.tdb: O2GAS, type code %, sha256 904325ae56bbb509…

68: PHASE O2GAS % 1 1 !
69: CONST O2GAS : O2 :!

Example references (2 of 2; assessments first):

doi:10.1007/s11669-015-0379-1 A. T. Dinsdale, A. Akhmetova, A. V. Khvan, N. Aristova, A Critical Assessment of Thermodynamic and Phase Diagram Data for the Ge-O System, J. Phase Equilib. Diffus. 36, 254-261 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2021.102299 I. Bajenova, A. Khvan, M. Derevyanko, N. Aristova, A. Dinsdale, A. Kondriatev, A. Pisch, Calphad, 74, 102299(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}
}