Bi–O system

81 accepted literature values from 1 paper(s) (experimental 74, model 6, unspecified 1); 1 calculated phase diagram(s). 5 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: JSON · CSV · interactive explorer · interactive phase diagram · phases (6) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	74
model	6
unspecified	1

Accepted values by property group
Property group	Values
invariant reaction	21
phase transition	5
formation	11
heat capacity / entropy / enthalpy	6
model expression	38

Calculated phase diagrams

Binary phase diagrams calculated with pycalphad 0.11.2 from the SGTE binary collection (Hallstedt 2025, CC BY 4.0). Evidence class: model.

Assessments with a calculated phase diagram
TDB file	Assessment	SHA-256	Links
BiO-95Ris-LB.tdb	D. Risold, B. Hallstedt, L.J. Gauckler, H.L. Lukas, S.G. Fries, J. Phase Equilib., 16, 223-34(1995). doi:10.1007/BF02667306	`77661bfd1c983207a3cf6a8d0a28007fb87424f1838742298c5fd6ec93295bfa`	viewer · TDB · JSON

Calculated three-phase invariants (model, mole fraction of the second component)
TDB file	T (K)	Phases at the invariant
BiO-95Ris-LB.tdb	1060.59	ION#2 (x(O) 0.0053) + ION (x(O) 0.5921) + BI2O3_C1 (x(O) 0.6)
BiO-95Ris-LB.tdb	1002.13	ION (x(O) 0.00307) + BI2O3_ALPHA (x(O) 0.6) + BI2O3_C1 (x(O) 0.6)
BiO-95Ris-LB.tdb	544.55	RHOMBOHEDRAL_A7 (x(O) 0) + ION (x(O) 0) + BI2O3_ALPHA (x(O) 0.6)

Convex hulls: Materials Project DFT hull · OQMD DFT hull

Invariant reactions (literature)

Invariant reactions reported in the literature for the Bi–O system (21)
T (K)	Reaction / phases	Compositions (mole fraction)	Class	Source	Location
1095	monotectic: L2 -> L1 + δ-Bi2O3 (monotectic)	δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Mehrotra 1976	Table I, p. 3, row 7 report
1093	monotectic: L2 -> L1 + δ-Bi2O3 (monotectic)	δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Rao 1975	Table I, p. 3, row 6 report
1090	monotectic: L2 -> L1 + δ-Bi2O3 (monotectic)	δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites B 1979	Table I, p. 3, row 8 report
1077	monotectic: L2 -> L1 + δ-Bi2O3 (monotectic)	δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites S 1984	Table I, p. 3, row 9 report
1061	monotectic: L2 -> L1 + δ-Bi2O3 (monotectic)	L2: O 0.592; L1: O 0.005; δ-Bi2O3: O 0.6	model	[1] Risold 1995	Table I, p. 3, row 10 report
1003	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites ref. 79Har	Table I, p. 3, row 16 report
1003	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Levin 1965 doi	Table I, p. 3, row 12 report
1003	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Korobeinikova 1976	Table I, p. 3, row 15 report
1003	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Cubicciotti 1967 doi	Table I, p. 3, row 13 report
1002	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites ref. 79Har	Table I, p. 3, row 17 report
1002	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6; L1: O 0.003	model	[1] Risold 1995	Table I, p. 3, row 25 report
1000	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Rao 1969 doi	Table I, p. 3, row 14 report
997	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Kameda 1991 doi	Table I, p. 3, row 23 report
997	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Kameda 1992 doi	Table I, p. 3, row 24 report
997	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Fitzner 1980 doi	Table I, p. 3, row 21 report
991	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Mehrotra 1976	Table I, p. 3, row 19 report
990	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Gattow 1962 doi	Table I, p. 3, row 11 report
980	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites B 1979	Table I, p. 3, row 20 report
978	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Rao 1971 doi	Table I, p. 3, row 18 report
974	polymorphic: δ-Bi2O3 -> α-Bi2O3 (+ L1) (solid state transition)	δ-Bi2O3: O 0.6; α-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Schaefer 1985	Table I, p. 3, row 22 report
544	eutectic: L1 -> Bi + α-Bi2O3 (eutectic)	L1: O 4.000e-7; Bi: O 0; α-Bi2O3: O 0.6	model	[1] Risold 1995	Table I, p. 3, row 26 report

Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from dft_parity.json.

Enthalpies of formation, Bi–O system (11)
Phase	Value	T (K)	Class	Source	Location
α-Bi2O3	-590.2 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites S 1984	Table 6, p. 5, row 8 report
α-Bi2O3	-587.5 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Sidorov 1980	Table 6, p. 5, row 4 report
α-Bi2O3	-581.6 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Cahen 1978	Table 6, p. 5, row 7 report
α-Bi2O3	-576.6 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Ditte 1892	Table 6, p. 5, row 1 report
α-Bi2O3	-573.9 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Mah 1961	Table 6, p. 5, row 3 report
α-Bi2O3	-570.3 kJ/mol (basis unstated)	298.15	unspecified	[1] Risold 1995	Table 6, p. 5, row 11 report
α-Bi2O3	-569 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Mixter 1909 doi	Table 6, p. 5, row 2 report
α-Bi2O3	-567.8 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Schaefer 1985	Table 6, p. 5, row 10 report
α-Bi2O3	-567.4 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Rao 1971 doi	Table 6, p. 5, row 5 report
α-Bi2O3	-563.4 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites S 1984	Table 6, p. 5, row 9 report
α-Bi2O3	-550.6 kJ/mol (basis unstated)	298.15	experimental	[1] Risold 1995 cites Chatterji 1973 doi	Table 6, p. 5, row 6 report

Other properties

Phase transition (5)

Phase transition, Bi–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Phase transition	1097 K	1097	congruent melting: L2 -> δ-Bi2O3 (melting point of Bi2O3) L2: O 0.6; δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites ref. 79Har	Table I, p. 3, row 4 report
Phase transition	1097 K	1097	congruent melting: L2 -> δ-Bi2O3 (melting point of Bi2O3) L2: O 0.6; δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Gattow 1964 doi	Table I, p. 3, row 1 report
Phase transition	1098 K	1098	congruent melting: L2 -> δ-Bi2O3 (melting point of Bi2O3) L2: O 0.6; δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Levin 1965 doi	Table I, p. 3, row 2 report
Phase transition	1098 K	1098	congruent melting: L2 -> δ-Bi2O3 (melting point of Bi2O3) L2: O 0.6; δ-Bi2O3: O 0.6	model	[1] Risold 1995	Table I, p. 3, row 5 report
Phase transition	1101 K	1101	congruent melting: L2 -> δ-Bi2O3 (melting point of Bi2O3) L2: O 0.6; δ-Bi2O3: O 0.6	experimental	[1] Risold 1995 cites Cubicciotti 1967 doi	Table I, p. 3, row 3 report

Heat capacity / entropy / enthalpy (6)

Heat capacity / entropy / enthalpy, Bi–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Entropy printed: S298	30 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	experimental	[1] Risold 1995 cites ref. 81Gor	Table 3, p. 4, row 2 report
Entropy printed: S298	30.2 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	experimental	[1] Risold 1995 cites C 1937	Table 3, p. 4, row 1 report
Entropy printed: S298	29.7 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	model	[1] Risold 1995	Table 3, p. 4, row 3 report
Heat capacity printed: Cp	22.68 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	experimental	[1] Risold 1995 cites ref. 81Gor	Table 3, p. 4, row 2 report
Heat capacity printed: Cp	22.4 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	experimental	[1] Risold 1995 cites C 1937	Table 3, p. 4, row 1 report
Heat capacity printed: Cp	22.42 J/mol-atom/K	298.15	α-Bi2O3 alloy: O 0.6	model	[1] Risold 1995	Table 3, p. 4, row 3 report

Model expression (38)

Model expression, Bi–O system
Property	Value	Phases / composition	Class	Source	Location
gibbs energy expression term printed: ΔG (A)	-545681 J/mol	L	experimental	[1] Risold 1995 cites Rao 1975	Table 7, p. 6, row 27 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	252.8 J/mol/K	L	experimental	[1] Risold 1995 cites Rao 1975	Table 7, p. 6, row 27 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	229.7 J/mol/K	L	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 36 report
gibbs energy expression term printed: ΔG (A)	-518007 J/mol	L	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 36 report
gibbs energy expression term printed: ΔG (A)	-373422 J/mol	L	experimental	[1] Risold 1995 cites Codron 1972	Table 7, p. 6, row 25 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	156.9 J/mol/K	L	experimental	[1] Risold 1995 cites Codron 1972	Table 7, p. 6, row 25 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	217.8 J/mol/K	L	experimental	[1] Risold 1995 cites Mehrotra 1976	Table 7, p. 6, row 31 report
gibbs energy expression term printed: ΔG (A)	-498900 J/mol	L	experimental	[1] Risold 1995 cites Mehrotra 1976	Table 7, p. 6, row 31 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	129.7 J/mol/K	L	experimental	[1] Risold 1995 cites ref. 79Hah	Table 7, p. 6, row 33 report
gibbs energy expression term printed: ΔG (A)	-415471 J/mol	L	experimental	[1] Risold 1995 cites ref. 79Hah	Table 7, p. 6, row 33 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	235.91 J/mol/K	L	experimental	[1] Risold 1995 cites S 1984	Table 7, p. 6, row 40 report
gibbs energy expression term printed: ΔG (A)	-520840 J/mol	L	experimental	[1] Risold 1995 cites S 1984	Table 7, p. 6, row 40 report
gibbs energy expression term printed: ΔG (A)	-581994 J/mol	α	experimental	[1] Risold 1995 cites Schaefer 1985	Table 7, p. 6, row 41 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	314.42 J/mol/K	α	experimental	[1] Risold 1995 cites Fitzner 1980 doi	Table 7, p. 6, row 37 report
gibbs energy expression term printed: ΔG (A)	-629608 J/mol	α	experimental	[1] Risold 1995 cites Rao 1971 doi	Table 7, p. 6, row 24 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	334.5 J/mol/K	α	experimental	[1] Risold 1995 cites Rao 1971 doi	Table 7, p. 6, row 24 report
gibbs energy expression term printed: ΔG (A)	-583592 J/mol	α	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 34 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	293.9 J/mol/K	α	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 34 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	293.4 J/mol/K	α	experimental	[1] Risold 1995 cites Kameda 1992 doi	Table 7, p. 6, row 45 report
gibbs energy expression term printed: ΔG (A)	-582520 J/mol	α	experimental	[1] Risold 1995 cites Kameda 1991 doi	Table 7, p. 6, row 43 report
gibbs energy expression term printed: ΔG (A)	-600990 J/mol	α	experimental	[1] Risold 1995 cites Mehrotra 1976	Table 7, p. 6, row 29 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	315.2 J/mol/K	α	experimental	[1] Risold 1995 cites Mehrotra 1976	Table 7, p. 6, row 29 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	265.4 J/mol/K	α, δ	experimental	[1] Risold 1995 cites Chatterji 1973 doi	Table 7, p. 6, row 28 report
gibbs energy expression term printed: ΔG (A)	-560196 J/mol	α, δ	experimental	[1] Risold 1995 cites Chatterji 1973 doi	Table 7, p. 6, row 28 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	267.8 J/mol/K	δ	experimental	[1] Risold 1995 cites Cahen 1978	Table 7, p. 6, row 32 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	253.72 J/mol/K	δ	experimental	[1] Risold 1995 cites S 1984	Table 7, p. 6, row 39 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	241.8 J/mol/K	δ	experimental	[1] Risold 1995 cites Schaefer 1985	Table 7, p. 6, row 42 report
gibbs energy expression term printed: ΔG (A)	-532247 J/mol	δ	experimental	[1] Risold 1995 cites Schaefer 1985	Table 7, p. 6, row 42 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	271.5 J/mol/K	δ	experimental	[1] Risold 1995 cites Mehrotra 1976	Table 7, p. 6, row 30 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	270.3 J/mol/K	δ	experimental	[1] Risold 1995 cites Fitzner 1980 doi	Table 7, p. 6, row 38 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	261.06 J/mol/K	δ	experimental	[1] Risold 1995 cites Kameda 1991 doi	Table 7, p. 6, row 44 report
gibbs energy expression term printed: ΔG (A)	-549700 J/mol	δ	experimental	[1] Risold 1995 cites Kameda 1991 doi	Table 7, p. 6, row 44 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	261.1 J/mol/K	δ	experimental	[1] Risold 1995 cites Kameda 1992 doi	Table 7, p. 6, row 46 report
gibbs energy expression term printed: ΔG (A)	-549700 J/mol	δ	experimental	[1] Risold 1995 cites Kameda 1992 doi	Table 7, p. 6, row 46 report
gibbs energy expression term printed: ΔG (A)	-543905 J/mol	δ	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 35 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	253.4 J/mol/K	δ	experimental	[1] Risold 1995 cites B 1979	Table 7, p. 6, row 35 report
gibbs energy expression term printed: ΔG (A)	-572613 J/mol	δ	experimental	[1] Risold 1995 cites Rao 1975	Table 7, p. 6, row 26 report
gibbs energy expression term printed: ΔG (B, coefficient of T)	227.3 J/mol/K	δ	experimental	[1] Risold 1995 cites Rao 1975	Table 7, p. 6, row 26 report

Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

D. Risold, B. Hallstedt, L. J. Gauckler, H. L. Lukas, S. G. Fries, The bismuth-oxygen system, JPE 16 (1995). doi:10.1007/bf02667306

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735569
R. Arróyave, J. Saal, D. Shin, ORCHID-Diagrams: calculated binary phase diagrams (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735859
R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735891
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 the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); 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). 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_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_phase_diagrams_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Diagrams: calculated binary phase diagrams}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735859},
  url       = {https://doi.org/10.5281/zenodo.23735859}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@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}
}