B–O phases

7 phases (tier B 1, tier C 1, liquid 1, gas 2, needs_review 2); 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 · full JSON · B–O system page · Markdown · field reference

Phases of the B–O system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
ALPHA_RHOMBO_B phase:b-o:b-alpha-rhombo		needs_review	stable in 1 of 1 calculated diagram(s): 300–1388 K, x(O) 0–0	0	1
BETA_RHOMBO_B phase:b-o:b-beta-rhombo		needs_review	stable in 1 of 1 calculated diagram(s): 1388–2347.99 K, x(O) 0–0	0	1
B2O3 phase:b-o:b2o3	B2O3 · hP15 · P3_121 (152)	tier B: DFT-supported (unique MP + OQMD match)	stable in 1 of 1 calculated diagram(s): 300–723 K, x(O) 0.6–0.6	1	1
B6O phase:b-o:b6o	B6P · hR14 · R-3m (166)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1060.3 K, x(O) 0.14286–0.14286	0	1
GAS phase:b-o:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300.5–4000 K, x(O) 0.317–1	0	1
LIQUID phase:b-o:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 723–4000 K, x(O) 0–0.6	1	1
O2GAS phase:b-o:o2gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–1128 K, x(O) 1–1	0	1

ALPHA_RHOMBO_B (B–O)

Id: phase:b-o:b-alpha-rhombo; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:RHOMBO; no_structure_token
Candidate (sgte_mmc2): alpha-B · hR12 · R-3m (166) — Hallstedt 2025 mmc2 row for ALPHA_RHOMBO_B: Si_nB
Candidate (tdb_comment): alpha-B · hR12 · R-3m — BO-23Pha.tdb: 'Prototype alpha-B (hR12, R-3m)'
Stoichiometry: B 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–1388 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-o:b-alpha-rhombo
tdb: tdb:BO-23Pha.tdb:ALPHA_RHOMBO_B

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

BO-23Pha.tdb: ALPHA_RHOMBO_B, type code %, sha256 52cca70a9ed43da1…

42: PHASE ALPHA_RHOMBO_B % 1 1 !
43: CONST ALPHA_RHOMBO_B : B : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase

BETA_RHOMBO_B (B–O)

Id: phase:b-o:b-beta-rhombo; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:RHOMBO; no_structure_token
Candidate (sgte_mmc2): beta-B · hR105 · R-3m (166) — Hallstedt 2025 mmc2 row for BETA_RHOMBO_B: beta-B
Candidate (tdb_comment): beta-B · hR105 · R-3m — BO-23Pha.tdb: 'Prototype beta-B (hR105, R-3m)'
Stoichiometry: B 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 1388–2347.99 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-o:b-beta-rhombo
tdb: tdb:BO-23Pha.tdb:BETA_RHOMBO_B

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

BO-23Pha.tdb: BETA_RHOMBO_B, type code %, sha256 52cca70a9ed43da1…

47: PHASE BETA_RHOMBO_B % 1 1 !
48: CONST BETA_RHOMBO_B : B : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase

B2O3 (B–O)

Id: phase:b-o:b2o3; status assigned
Structure: B2O3 · hP15 · P3_121 (152); type st:b2o3-hp15; tier B: DFT-supported (unique MP + OQMD match); confidence high
Stoichiometry: B 0.4000, O 0.6000
Stability: stable in 1 of 1 calculated diagram(s): 300–723 K, x(O) 0.6–0.6
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:b-o:b2o3
mp: mp:mp-aaaaaalu
oqmd: oqmd:oqmd-9107
paper: paper:10.1111/jace.18958:B2O3
tdb: tdb:BO-23Pha.tdb:B2O3

TDB models of B2O3 (1): PHASE and CONSTITUENT statements as written

BO-23Pha.tdb: B2O3, type code %, sha256 52cca70a9ed43da1…

57: PHASE B2O3 % 2 2 3 !
58: CONST B2O3 : B : O : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase; reports values for this phase

B6O (B–O)

Id: phase:b-o:b6o; status assigned
Structure: B6P · hR14 · R-3m (166); type st:b6p-hr14; 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 (mp_oqmd_space_groups_differ, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: B 0.8571, O 0.1429
Stability: stable in 1 of 1 calculated diagram(s): 300–1060.3 K, x(O) 0.14286–0.14286
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-o:b6o
tdb: tdb:BO-23Pha.tdb:B6O

TDB models of B6O (1): PHASE and CONSTITUENT statements as written

BO-23Pha.tdb: B6O, type code %, sha256 52cca70a9ed43da1…

52: PHASE B6O % 2 6 1 !
53: CONST B6O : B : O : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase

GAS (B–O)

Id: phase:b-o:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300.5–4000 K, x(O) 0.317–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-o:gas
tdb: tdb:BO-23Pha.tdb:GAS

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

BO-23Pha.tdb: GAS, type code %, sha256 52cca70a9ed43da1…

63: PHASE GAS:G % 1 1 !
64: CONST GAS:G : B B2 BO BO2 B2O B2O2 B2O3 O O2 O3 : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase

LIQUID (B–O)

Id: phase:b-o:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 723–4000 K, x(O) 0–0.6
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:b-o:liquid
paper: paper:10.1111/jace.18958:liquid
tdb: tdb:BO-23Pha.tdb:LIQUID

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

BO-23Pha.tdb: LIQUID, type code %, sha256 52cca70a9ed43da1…

37: PHASE LIQUID:L % 1 1 !
38: CONST LIQUID:L : B B2O3 O : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
assessment that models this phase; reports values for this phase

O2GAS (B–O)

Id: phase:b-o:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1128 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:b-o:o2gas
tdb: tdb:BO-23Pha.tdb:O2GAS

TDB models of O2GAS (1): PHASE and CONSTITUENT statements as written

BO-23Pha.tdb: O2GAS, type code %, sha256 52cca70a9ed43da1…

60: PHASE O2GAS % 1 1 !
61: CONST O2GAS : O2 :!

Example references (1 of 1; assessments first):

doi:10.1111/jace.18958 David Pham, Fangyuan Gai, Jacob Rochester, Joseph H. Dycus, James M. LeBeau, Venkateswara Rao Manga et al., Thermodynamic assessment within the Zr–B–C–O quaternary system, J Am Ceram Soc. 106, 3127-3140 (2023).
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}
}