Am–O system

79 accepted literature values from 2 paper(s) (experimental 65, model 14); 2 calculated phase diagram(s). 7 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 (10) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	65
model	14

Accepted values by property group
Property group	Values
phase transition	3
phase equilibrium	3
formation	6
heat capacity / entropy / enthalpy	6
activity / EMF / Gibbs energy	2
crystal structure	56
other property	3

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
AmO-11Got.tdb	P. Gotcu-Freis, J.-Y. Colle, C. Gueneau, N. Dupin, B. Sundman, R.J.M. Konings, J. Nucl. Mater., 414, 408-21(2011). doi:10.1016/j.jnucmat.2011.05.014	`1d255c8beb1f09b86cb0fe1dcd18d2de9a5964359d343f52b49debc5faa34e02`	viewer · TDB · JSON
AmO-17Epi.tdb	E. Epifano, C. Gueneau, R.C. Belin, R. Vauchy, F. Lebreton, J.-C. Richaud, A. Joly, C. Valot, P.M. Martin, Inorg. Chem., 56, 7416-32(2017). doi:10.1021/acs.inorgchem.7b00572	`ca6b8ebfc913b566617c00f6ae6f7772a41cc7368b15f7c4bcc13cefd460be52`	viewer · TDB · JSON

Calculated three-phase invariants (model, mole fraction of the second component)
TDB file	T (K)	Phases at the invariant
AmO-11Got.tdb	2306.9	ION (x(O) 0.62896) + AMO2_C1 (x(O) 0.63641) + GAS (x(O) 0.99887)
AmO-17Epi.tdb	2265.05	ION (x(O) 0.62919) + AMO2_C1 (x(O) 0.63844) + GAS (x(O) 0.99923)

Convex hulls: CALPHAD hull AmO-11Got

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, Am–O system (6)
Phase	Value	T (K)	Class	Source	Location
Am2O3	-338.54 kJ/mol-atom	298.15	model	[1] Gotcu-Freis 2011	Table 3, p. 11, row 1 report
Am2O3	-338.08 kJ/mol-atom ± 1.6	298.15	model	[1] Gotcu-Freis 2011 cites Konings doi	Table 3, p. 11, row 3 report
Am2O3	-338.08 kJ/mol-atom ± 1.6	298.15	model	[1] Gotcu-Freis 2011 cites Silva 2004	Table 3, p. 11, row 2 report
AmO2	-310.767 kJ/mol-atom ± 1	298.15	model	[1] Gotcu-Freis 2011 cites Silva 2004	Table 3, p. 11, row 5 report
AmO2	-310.733 kJ/mol-atom ± 1	298.15	model	[1] Gotcu-Freis 2011 cites Konings doi	Table 3, p. 11, row 6 report
AmO2	-310.567 kJ/mol-atom	298.15	model	[1] Gotcu-Freis 2011	Table 3, p. 11, row 4 report

Other properties

Phase transition (3)

Phase transition, Am–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Phase transition	1315 K	1315	other	model	[2] Epifano 2017	p. 14 report	The temperature stability for this phase was extended here up to 1315 K.
Phase transition	2386 K	2386	AmO2-x	experimental	[2] Epifano 2017 cites ref. 25	p. 4 report	The values are 2481 ± 15 K for A-Am2O3 and 2386 K for AmO2-x (the O/Am ratio reached during the melting process is unknown).
Phase transition	2481 K	2481	A-Am2O3	experimental	[2] Epifano 2017 cites ref. 25	p. 4 report	The values are 2481 ± 15 K for A-Am2O3 and 2386 K for AmO2-x (the O/Am ratio reached during the melting process is unknown).

Phase equilibrium (3)

Phase equilibrium, Am–O system
Property	T (K)	Phases / composition	Class	Source	Location
Phase assemblage	1101.5	C-AmO1.61+x + A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 3, p. 3, row 2 report
Phase assemblage	1273	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 3, p. 3, row 4 report
Phase assemblage	2481	A-Am2O3 + liquid alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 25	Table 3, p. 3, row 13 report

Heat capacity / entropy / enthalpy (6)

Heat capacity / entropy / enthalpy, Am–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Entropy printed: S°(298.15 K)	26.72 J/mol-atom/K ± 1	298.15	Am2O3 alloy: O 0.6	model	[1] Gotcu-Freis 2011 cites Konings doi	Table 3, p. 11, row 3 report
Entropy printed: S°(298.15 K)	32 J/mol-atom/K ± 3	298.15	Am2O3 alloy: O 0.6	model	[1] Gotcu-Freis 2011 cites Silva 2004	Table 3, p. 11, row 2 report
Entropy printed: S°(298.15 K)	27.342 J/mol-atom/K	298.15	Am2O3 alloy: O 0.6	model	[1] Gotcu-Freis 2011	Table 3, p. 11, row 1 report
Entropy printed: S°(298.15 K)	22.3333 J/mol-atom/K ± 3.33333	298.15	AmO2 alloy: O 0.666667	model	[1] Gotcu-Freis 2011 cites Silva 2004	Table 3, p. 11, row 5 report
Entropy printed: S°(298.15 K)	23.3533 J/mol-atom/K	298.15	AmO2 alloy: O 0.666667	model	[1] Gotcu-Freis 2011	Table 3, p. 11, row 4 report
Entropy printed: S°(298.15 K)	25.1667 J/mol-atom/K ± 1.66667	298.15	AmO2 alloy: O 0.666667	model	[1] Gotcu-Freis 2011 cites Konings doi	Table 3, p. 11, row 6 report

Activity / EMF / Gibbs energy (2)

Activity / EMF / Gibbs energy, Am–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Chemical potential printed: ΔG̅ O2	-140 kJ mol-1	1500	AmO2-x + A-Am2O3	experimental	[2] Epifano 2017	p. 16 report	Second, the AmO2-x → AmO2-x + A-Am2O3 phase transition was observed at 1500 K by imposing the calculated oxygen potential ΔG̅ O2 ∼ -140 kJ mol-1.
Vapour pressure printed: pO2	2.000e-5 atm	1500	A-Am2O3 + AmO2-x	model	[2] Epifano 2017	p. 6 report	The main goal was to observe the hexagonal sesquioxide AAm2O3 at T = 1500 K. According to the thermodynamic computations, the phase transition should occur at this temperature under pO2 ≈ 2 × 10-5 atm.

Crystal structure (56)

Crystal structure, Am–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Lattice a	3.821 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 10	Table 1, p. 2, row 18 report
Lattice a	3.815 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 15	Table 1, p. 2, row 16 report
Lattice a	3.81 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 16	Table 1, p. 2, row 17 report
Lattice a	3.805 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 15 report
Lattice a	5.375 Å ± 0.001	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 18	Table 1, p. 2, row 6 report
Lattice a	5.3772 Å ± 4.000e-4	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 2 report
Lattice a	5.373 Å ± 0.002	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 17	Table 1, p. 2, row 5 report
Lattice a	5.376 Å ± 0.001	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 10	Table 1, p. 2, row 7 report
Lattice a	5.3724 Å ± 4.000e-4	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 15	Table 1, p. 2, row 3 report
Lattice a	5.3897 Å ± 2.000e-4	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 16	Table 1, p. 2, row 4 report
Lattice a	5.377 Å ± 0.003	298.15	AmO2-x	experimental	[2] Epifano 2017 cites ref. 8	Table 1, p. 2, row 1 report
Lattice a	14.38 Å	298.15	B-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 19 report
Lattice a	11.023 Å	298.15	C-AmO1.5+x	experimental	[2] Epifano 2017 cites ref. 15	Table 1, p. 2, row 13 report
Lattice a	11.02 Å	298.15	C-AmO1.5+x	experimental	[2] Epifano 2017 cites ref. 16	Table 1, p. 2, row 14 report
Lattice a	11.03 Å ± 0.01	298.15	C-AmO1.5+x	experimental	[2] Epifano 2017 cites ref. 9	Table 1, p. 2, row 11 report
Lattice a	11.013 Å	298.15	C-AmO1.5+x	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 12 report
Lattice a	10.966 Å ± 0.005	298.15	C-AmO1.61+x	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 8 report
Lattice a	10.97 Å ± 0.02	298.15	C-AmO1.61+x	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 10 report
Lattice a	10.92 Å ± 0.02	298.15	C-AmO1.61+x	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 9 report
Lattice a	5.377 Å ± 0.001	303	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 18 report
Lattice a	5.375 Å	303	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 20 report
Lattice a	5.383 Å ± 0.001	373	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 17 report
Lattice a	5.381 Å	423	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 21 report
Lattice a	5.389 Å ± 0.001	473	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 16 report
Lattice a	5.396 Å ± 0.001	573	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 15 report
Lattice a	5.389 Å	573	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 22 report
Lattice a	5.402 Å ± 0.001	673	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 14 report
Lattice a	5.396 Å	700	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 23 report
Lattice a	5.408 Å ± 0.001	773	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 13 report
Lattice a	5.403 Å	823	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 24 report
Lattice a	5.414 Å ± 0.001	873	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 12 report
Lattice a	5.409 Å	923	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 25 report
Lattice a	5.418 Å ± 0.001	973	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 11 report
Lattice a	5.415 Å	1023	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 26 report
Lattice a	5.428 Å ± 0.001	1073	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 10 report
Lattice a	5.421 Å	1120	UNKNOWN	experimental	[2] Epifano 2017 cites ref. 11	Table 6, p. 10, row 27 report
Lattice a	5.436 Å ± 0.001	1173	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 9 report
Lattice a	5.444 Å ± 0.001	1273	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 8 report
Lattice a	5.455 Å ± 0.001	1373	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 7 report
Lattice a	5.468 Å ± 0.001	1473	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 6 report
Lattice a	5.527 Å ± 0.001	1500	AmO2-x	experimental	[2] Epifano 2017	Table 6, p. 10, row 19 report
Lattice a	5.483 Å ± 0.001	1573	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 5 report
Lattice a	5.497 Å ± 0.001	1673	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 4 report
Lattice a	5.511 Å ± 0.001	1773	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 3 report
Lattice a	5.522 Å ± 0.001	1873	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 2 report
Lattice a	5.527 Å ± 0.001	1894	UNKNOWN	experimental	[2] Epifano 2017	Table 6, p. 10, row 1 report
Lattice b	3.821 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 10	Table 1, p. 2, row 18 report
Lattice b	3.815 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 15	Table 1, p. 2, row 16 report
Lattice b	3.81 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 16	Table 1, p. 2, row 17 report
Lattice b	3.805 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 15 report
Lattice b	3.52 Å	298.15	B-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 19 report
Lattice c	5.984 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 10	Table 1, p. 2, row 18 report
Lattice c	5.975 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 15	Table 1, p. 2, row 16 report
Lattice c	5.957 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 16	Table 1, p. 2, row 17 report
Lattice c	5.96 Å	298.15	A-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 15 report
Lattice c	8.92 Å	298.15	B-Am2O3 alloy: O 0.6	experimental	[2] Epifano 2017 cites ref. 6	Table 1, p. 2, row 19 report

Other property (3)

Other property, Am–O system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Other printed: O/Am	1.67 unspecified	1220	AmO1.61+x + AmO2-x	experimental	[2] Epifano 2017	p. 12 report	• A point on the phase boundary between AmO1.61+x and the biphasic region AmO2-x/AmO1.61+x: T = 1220 K and O/Am = 1.67;
Other printed: O/Am	1.67 unspecified	1220	C-AmO1.61+x	experimental	[2] Epifano 2017	p. 11 report	For the phase boundary where the C-AmO1.61+x phase precipitates at 1220 K, the evaluated O/Am ratio is 1.67.
Other printed: O/Am	1.59 unspecified	1500	AmO2-x + A-Am2O3	experimental	[2] Epifano 2017	p. 12 report	• The point on the phase boundary between AmO2-x and the biphasic region AmO2-x/A-Am2O3: T = 1500 K and O/Am = 1.59;

Sources

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

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). doi:10.1016/j.jnucmat.2011.05.014
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). doi:10.1021/acs.inorgchem.7b00572

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}
}