O–Ru phases

7 phases (tier A 4, liquid 1, gas 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 · O–Ru system page · Markdown · field reference

Phases of the O–Ru system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:o-ru:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
FCC_A1 phase:o-ru:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
GAS phase:o-ru:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 1822–4000 K, x(O) 0.80885–0.97927	3	1
HCP_A3 phase:o-ru:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–3999.5 K, x(O) 0–0	0	1
ION phase:o-ru:ion	liquid	liquid	stable in 1 of 1 calculated diagram(s): 2607–4000 K, x(O) 0–0	0	1
O2GAS phase:o-ru:o2gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–635 K, x(O) 1–1	0	1
RUO2_C4 phase:o-ru:ruo2-c4	TiO2 · C4 · tP6 · P4_2/mnm (136)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–635 K, x(O) 0.66667–0.66667	7	1

BCC_A2 (O–Ru)

Id: phase:o-ru:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: Ru 1.0000
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:o-ru:bcc-a2
tdb: tdb:RuO-18Gos.tdb:BCC_A2

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

RuO-18Gos.tdb: BCC_A2, type code %B, sha256 fa4c02e7ef6859bb…

47: PHASE BCC_A2 %B 2 1 3 !
48: CONST BCC_A2 : RU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase

FCC_A1 (O–Ru)

Id: phase:o-ru:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Ru 1.0000
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:o-ru:fcc-a1
tdb: tdb:RuO-18Gos.tdb:FCC_A1

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

RuO-18Gos.tdb: FCC_A1, type code %A, sha256 fa4c02e7ef6859bb…

42: PHASE FCC_A1 %A 2 1 1 !
43: CONST FCC_A1 : RU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase

GAS (O–Ru)

Id: phase:o-ru:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1822–4000 K, x(O) 0.80885–0.97927
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:o-ru:gas
paper: paper:10.1016/j.jnucmat.2017.12.034:Gas
tdb: tdb:RuO-18Gos.tdb:GAS

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

RuO-18Gos.tdb: GAS, type code %, sha256 fa4c02e7ef6859bb…

63: PHASE GAS:G % 1 1 !
64: CONST GAS:G : O O2 O3 RU RUO RUO2 RUO3 RUO4 : !

Example references (3 of 3; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase; reports values for this phase
doi:10.1021/j100805a042 Wayne E. Bell, M. Tagami, HIGH-TEMPERATURE CHEMISTRY OF THE RUTHENIUM—OXYGEN SYSTEM<sup>1</sup>, J. Phys. Chem. 67, 2432-2436 (1963).
cited as the source of values for this phase
doi:10.1595/003214065x925156 J. C. Chaston, Reactions of Oxygen with the Platinum Metals, Platinum Metals Review 9, 51-56 (1965).
cited as the source of values for this phase

HCP_A3 (O–Ru)

Id: phase:o-ru:hcp-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stoichiometry: Ru 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–3999.5 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:o-ru:hcp-a3
tdb: tdb:RuO-18Gos.tdb:HCP_A3

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

RuO-18Gos.tdb: HCP_A3, type code %A, sha256 fa4c02e7ef6859bb…

52: PHASE HCP_A3 %A 2 1 0.5 !
53: CONST HCP_A3 : RU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase

ION (O–Ru)

Id: phase:o-ru:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 2607–4000 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:o-ru:ion
tdb: tdb:RuO-18Gos.tdb:ION

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

RuO-18Gos.tdb: ION, type code %, sha256 fa4c02e7ef6859bb…

37: PHASE ION:Y % 2 1 1 !
38: CONST ION:Y : RU+4 : O-2 VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase

O2GAS (O–Ru)

Id: phase:o-ru:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–635 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:o-ru:o2gas
tdb: tdb:RuO-18Gos.tdb:O2GAS

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

RuO-18Gos.tdb: O2GAS, type code %, sha256 fa4c02e7ef6859bb…

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

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase

RUO2_C4 (O–Ru)

Id: phase:o-ru:ruo2-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 1 of 1 calculated diagram(s): 300–635 K, x(O) 0.66667–0.66667
Literature: 7 values (7 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:o-ru:ruo2-c4
paper: paper:10.1016/j.jnucmat.2017.12.034:RuO2
tdb: tdb:RuO-18Gos.tdb:RUO2_C4

TDB models of RUO2_C4 (1): PHASE and CONSTITUENT statements as written

RuO-18Gos.tdb: RUO2_C4, type code %, sha256 fa4c02e7ef6859bb…

57: PHASE RUO2_C4:I % 2 1 2 !
58: CONST RUO2_C4:I : RU+4 : O-2 : !

Example references (5 of 5; assessments first):

doi:10.1016/j.jnucmat.2017.12.034 S. Gossé, S. Bordier, C. Guéneau, E. Brackx, R. Domenger, J. Rogez, Thermodynamic assessment of the rhodium-ruthenium-oxygen (Rh-Ru-O) system, Journal of Nuclear Materials 500, 252-264 (2018).
assessment that models this phase; reports values for this phase
doi:10.1016/0040-6031(88)87197-1 E.H.P. Cordfunke, R.J.M. Konings, The enthalpy of formation of RuO2, Thermochimica Acta 129, 63-69 (1988).
cited as the source of values for this phase
doi:10.1021/j100805a042 Wayne E. Bell, M. Tagami, HIGH-TEMPERATURE CHEMISTRY OF THE RUTHENIUM—OXYGEN SYSTEM<sup>1</sup>, J. Phys. Chem. 67, 2432-2436 (1963).
cited as the source of values for this phase
doi:10.1103/physrevb.70.184115 M. E. Grillo, Stability of corundum- versus rutile-type structures of ruthenium and rhodium oxides, Phys. Rev. B 70 (2004).
cited as the source of values for this phase
doi:10.1515/htmp.2000.19.1.11 Κ. T. Jacob,, T. Uda,, Τ. H. Okabe,, Y. Waseda,, The Standard Enthalpy and Entropy of Formation of Rh2O3 - A Third-Law Optimization, High Temperature Materials and Processes 19, 11-16 (2000).
cited as the source of values for 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}
}