Am–O phases

10 phases (tier A 5, liquid 2, gas 2, needs_review 1); 6 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 · Am–O system page · Markdown · field reference

Phases of the Am–O system (10)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
AM2O3_D52 phase:am-o:am2o3-d52	A-La2O3 · D5_2 · hP5 · P-3m1 (164)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–675 K, x(O) 0.6–0.6	0	2
AMO1_62_D53 phase:am-o:amo1-d53-62		needs_review	not stable in 2 calculated diagram(s)	0	2
AMO2_C1 phase:am-o:amo2-c1	CaF2 · C1 · cF12 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2306.9 K, x(O) 0.62168–0.66667	0	2
BCC_A2 phase:am-o:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 2 calculated diagram(s)	0	2
DHCP phase:am-o:dhcp-a3	alpha-La · A3' · hP4 · P6_3/mmc (194)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–675 K, x(O) 0–0	0	2
FCC_A1 phase:am-o:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 2 calculated diagram(s)	0	2
GAS phase:am-o:gas	gas	gas	stable in 2 of 2 calculated diagram(s): 300.71–2500 K, x(O) 0–1	0	2
ION phase:am-o:ion	liquid	liquid	stable in 2 of 2 calculated diagram(s): 2210.05–2500 K, x(O) 0–0.62919	0	2
LIQUID phase:am-o:liquid	liquid	liquid	not stable in 2 calculated diagram(s)	1	2
O2GAS phase:am-o:o2gas	gas	gas	stable in 2 of 2 calculated diagram(s): 300–1185 K, x(O) 1–1	0	2

AM2O3_D52 (Am–O)

Id: phase:am-o:am2o3-d52; status assigned
Structure: A-La2O3 · D5_2 · hP5 · P-3m1 (164); type st:d5-2-a-la2o3-hp5; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–675 K, x(O) 0.6–0.6
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:am2o3-d52
tdb: tdb:AmO-11Got.tdb:AM2O3_D52, tdb:AmO-17Epi.tdb:AM2O3_D52

TDB models of AM2O3_D52 (2): PHASE and CONSTITUENT statements as written

AmO-11Got.tdb: AM2O3_D52, type code %, sha256 1d255c8beb1f09b8…

65: PHASE AM2O3_D52:I % 2 2 3 !
66: CONST AM2O3_D52:I : AM+3 : O-2 : !

AmO-17Epi.tdb: AM2O3_D52, type code %, sha256 ca6b8ebfc913b566…

64: PHASE AM2O3_D52:I % 2 2 3 !
65: CONST AM2O3_D52:I : AM+3 : O-2 : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

AMO1_62_D53 (Am–O)

Id: phase:am-o:amo1-d53-62; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:stoichiometry_contradicts_D5_3; stoichiometry_contradicts_D5_3:AmO-11Got.tdb; unrecognised_name_tokens:62
Candidate (name_token): Mn2O3 · D5_3 · cI80 · Ia-3 (206) — Strukturbericht/word 'D53' in the TDB name
Candidate (sgte_mmc2): Mn2O3 · D5_3 · cI80 · Ia-3 (206) — Hallstedt 2025 mmc2 row for AMO1_62_D53: AmO1.62
Candidate (tdb_comment): Mn2O3 · cI80 · Ia-3 — AmO-11Got.tdb: 'Prototype Mn2O3 (cI80, Ia-3)'
Candidate (tdb_comment): Mn2O3 · cI80 · Ia-3 — AmO-17Epi.tdb: 'Prototype Mn2O3 (cI80, Ia-3)'
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:am-o:amo1-d53-62
tdb: tdb:AmO-11Got.tdb:AMO1_62_D53, tdb:AmO-17Epi.tdb:AMO1_62_D53

TDB models of AMO1_62_D53 (2): PHASE and CONSTITUENT statements as written

AmO-11Got.tdb: AMO1_62_D53, type code %, sha256 1d255c8beb1f09b8…

70: PHASE AMO1_62_D53 % 2 1 1.62 !
71: CONST AMO1_62_D53 : AM : O : !

AmO-17Epi.tdb: AMO1_62_D53, type code %, sha256 ca6b8ebfc913b566…

69: PHASE AMO1_62_D53:I % 3 2 3 1 !
70: CONST AMO1_62_D53:I : AM+3 AM+4 : O-2 : O-2 VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

AMO2_C1 (Am–O)

Id: phase:am-o:amo2-c1; status assigned
Structure: CaF2 · C1 · cF12 · Fm-3m (225); type st:c1-caf2-cf12; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–2306.9 K, x(O) 0.62168–0.66667
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:amo2-c1
tdb: tdb:AmO-11Got.tdb:AMO2_C1, tdb:AmO-17Epi.tdb:AMO2_C1

TDB models of AMO2_C1 (2): PHASE and CONSTITUENT statements as written

AmO-11Got.tdb: AMO2_C1, type code %, sha256 1d255c8beb1f09b8…

60: PHASE AMO2_C1:I % 3 1 2 1 !
61: CONST AMO2_C1:I : AM+3 AM+4 : O-2 VA : O-2 VA : !

AmO-17Epi.tdb: AMO2_C1, type code %, sha256 ca6b8ebfc913b566…

59: PHASE AMO2_C1:I % 3 1 2 1 !
60: CONST AMO2_C1:I : AM+3 AM+4 : O-2 VA : O-2 VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

BCC_A2 (Am–O)

Id: phase:am-o:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: Am 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:am-o:bcc-a2
tdb: tdb:AmO-11Got.tdb:BCC_A2, tdb:AmO-17Epi.tdb:BCC_A2

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

AmO-11Got.tdb: BCC_A2, type code %B, sha256 1d255c8beb1f09b8…

50: PHASE BCC_A2 %B 2 1 3 !
51: CONST BCC_A2 : AM : VA : !

AmO-17Epi.tdb: BCC_A2, type code %B, sha256 ca6b8ebfc913b566…

49: PHASE BCC_A2 %B 2 1 3 !
50: CONST BCC_A2 : AM : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

DHCP (Am–O)

Id: phase:am-o:dhcp-a3; status assigned
Structure: alpha-La · A3' · hP4 · P6_3/mmc (194); type st:a3-alpha-la-hp4; tier A: standard phase name; confidence high
Stoichiometry: Am 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 300–675 K, x(O) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:dhcp-a3
tdb: tdb:AmO-11Got.tdb:DHCP, tdb:AmO-17Epi.tdb:DHCP

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

AmO-11Got.tdb: DHCP, type code %, sha256 1d255c8beb1f09b8…

55: PHASE DHCP % 1 1 !
56: CONST DHCP : AM : !

AmO-17Epi.tdb: DHCP, type code %, sha256 ca6b8ebfc913b566…

54: PHASE DHCP % 1 1 !
55: CONST DHCP : AM : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

FCC_A1 (Am–O)

Id: phase:am-o:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Am 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:am-o:fcc-a1
tdb: tdb:AmO-11Got.tdb:FCC_A1, tdb:AmO-17Epi.tdb:FCC_A1

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

AmO-11Got.tdb: FCC_A1, type code %A, sha256 1d255c8beb1f09b8…

45: PHASE FCC_A1 %A 2 1 1 !
46: CONST FCC_A1 : AM : VA : !

AmO-17Epi.tdb: FCC_A1, type code %A, sha256 ca6b8ebfc913b566…

44: PHASE FCC_A1 %A 2 1 1 !
45: CONST FCC_A1 : AM : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

GAS (Am–O)

Id: phase:am-o:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300.71–2500 K, x(O) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:gas
tdb: tdb:AmO-11Got.tdb:GAS, tdb:AmO-17Epi.tdb:GAS

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

AmO-11Got.tdb: GAS, type code %, sha256 1d255c8beb1f09b8…

76: PHASE GAS:G % 1 1 !
77: CONST GAS:G : AM AMO AMO2 O O2 O3 : !

AmO-17Epi.tdb: GAS, type code %, sha256 ca6b8ebfc913b566…

75: PHASE GAS:G % 1 1 !
76: CONST GAS:G : AM AMO AMO2 O O2 O3 : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

ION (Am–O)

Id: phase:am-o:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 2210.05–2500 K, x(O) 0–0.62919
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:ion
tdb: tdb:AmO-11Got.tdb:ION, tdb:AmO-17Epi.tdb:ION

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

AmO-11Got.tdb: ION, type code %, sha256 1d255c8beb1f09b8…

40: PHASE ION:Y % 2 1 1 !
41: CONST ION:Y : AM+3 : O-2 VA O : !

AmO-17Epi.tdb: ION, type code %, sha256 ca6b8ebfc913b566…

39: PHASE ION:Y % 2 1 1 !
40: CONST ION:Y : AM+3 : O-2 VA O : !

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase

LIQUID (Am–O)

Id: phase:am-o:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stoichiometry: Am 1.0000
Stability: not stable in 2 calculated diagram(s)
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:am-o:liquid
paper: paper:10.1021/acs.inorgchem.7b00572:liquid
tdb: tdb:AmO-11Got.tdb:LIQUID, tdb:AmO-17Epi.tdb:LIQUID

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

AmO-11Got.tdb: LIQUID, type code %, sha256 1d255c8beb1f09b8…

37: PHASE LIQUID:L % 1 1 !
38: CONST LIQUID:L : AM : !

AmO-17Epi.tdb: LIQUID, type code %, sha256 ca6b8ebfc913b566…

36: PHASE LIQUID:L % 1 1 !
37: CONST LIQUID:L : AM : !

Example references (2 of 2; assessments first):

doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
assessment that models this phase; reports values for this phase
doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase

O2GAS (Am–O)

Id: phase:am-o:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–1185 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:am-o:o2gas
tdb: tdb:AmO-11Got.tdb:O2GAS, tdb:AmO-17Epi.tdb:O2GAS

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

AmO-11Got.tdb: O2GAS, type code %, sha256 1d255c8beb1f09b8…

73: PHASE O2GAS % 1 1 !
74: CONST O2GAS : O2 :!

AmO-17Epi.tdb: O2GAS, type code %, sha256 ca6b8ebfc913b566…

72: PHASE O2GAS % 1 1 !
73: CONST O2GAS : O2 :!

Example references (2 of 2; assessments first):

doi:10.1016/j.jnucmat.2011.05.014 P. Gotcu-Freis, J.-Y. Colle, C. Guéneau, N. Dupin, B. Sundman, R.J.M. Konings, A thermodynamic study of the Pu–Am–O system, Journal of Nuclear Materials 414, 408-421 (2011).
assessment that models this phase
doi:10.1021/acs.inorgchem.7b00572 Enrica Epifano, Christine Guéneau, Renaud C. Belin, Romain Vauchy, Florent Lebreton, Jean-Christophe Richaud et al., Insight into the Am–O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling, Inorg. Chem. 56, 7416-7432 (2017).
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}
}