Np–Pu phases

11 phases (tier A 6, liquid 1, needs_review 4); 10 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 · Np–Pu system page · Markdown · field reference

Phases of the Np–Pu system (11)
Phase	Structure	Basis	Stability (calculated)	TDB models
TETRAGONAL_A6 phase:np-pu:a6-tetragonal	In · A6 · tI2 · I4/mmm (139)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 700.79–764.96 K, x(Pu) 0.94627–1	1
TETRAG_AD phase:np-pu:ad-tetrag	beta-Np · A_d · tP4 · P4/nmm (129)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 549.1–855.55 K, x(Pu) 0–0.20886	1
BCC_A2 phase:np-pu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 709.96–913 K, x(Pu) 0–1	1
FCC_A1 phase:np-pu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 593.44–829.9 K, x(Pu) 0.95063–1	1
HCP_A3 phase:np-pu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
LIQUID phase:np-pu:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 831.62–4000 K, x(Pu) 0–1	1
NPPU_ETA phase:np-pu:nppu-eta		needs_review	stable in 1 of 1 calculated diagram(s): 554.55–776.31 K, x(Pu) 0.52046–0.97329	1
ORTHO_AC phase:np-pu:ortho-ac	alpha-Np · A_c · oP8 · Pnma (62)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–555.02 K, x(Pu) 0–0.05172	1
ALPHA_PU phase:np-pu:pu-alpha		needs_review	stable in 1 of 1 calculated diagram(s): 300–572.02 K, x(Pu) 0.08645–1	1
BETA_PU phase:np-pu:pu-beta		needs_review	stable in 1 of 1 calculated diagram(s): 397.62–820.42 K, x(Pu) 0.20885–1	1
GAMMA_PU phase:np-pu:pu-gamma		needs_review	stable in 1 of 1 calculated diagram(s): 402.91–599.83 K, x(Pu) 0.98334–1	1

TETRAGONAL_A6 (Np–Pu)

Id: phase:np-pu:a6-tetragonal; status assigned
Structure: In · A6 · tI2 · I4/mmm (139); type st:a6-in-ti2; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 700.79–764.96 K, x(Pu) 0.94627–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:a6-tetragonal
tdb: tdb:NpPu-10Kur.tdb:TETRAGONAL_A6

TDB models of TETRAGONAL_A6 (1): PHASE and CONSTITUENT statements as written

NpPu-10Kur.tdb: TETRAGONAL_A6, type code %, sha256 4debc868e0be8e01…

42: PHASE TETRAGONAL_A6 % 1 1 !
43: CONST TETRAGONAL_A6 : NP PU% : !

TETRAG_AD (Np–Pu)

Id: phase:np-pu:ad-tetrag; status assigned
Structure: beta-Np · A_d · tP4 · P4/nmm (129); type st:a-d-beta-np-tp4; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 549.1–855.55 K, x(Pu) 0–0.20886
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:ad-tetrag
tdb: tdb:NpPu-10Kur.tdb:TETRAG_AD

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

NpPu-10Kur.tdb: TETRAG_AD, type code %, sha256 4debc868e0be8e01…

52: PHASE TETRAG_AD % 1 1 !
53: CONST TETRAG_AD : NP% PU : !

BCC_A2 (Np–Pu)

Id: phase:np-pu:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 709.96–913 K, x(Pu) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:bcc-a2
tdb: tdb:NpPu-10Kur.tdb:BCC_A2

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

NpPu-10Kur.tdb: BCC_A2, type code %B, sha256 4debc868e0be8e01…

32: PHASE BCC_A2 %B 2 1 3 !
33: CONST BCC_A2 : NP% PU% : VA : !

FCC_A1 (Np–Pu)

Id: phase:np-pu:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 593.44–829.9 K, x(Pu) 0.95063–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:fcc-a1
tdb: tdb:NpPu-10Kur.tdb:FCC_A1

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

NpPu-10Kur.tdb: FCC_A1, type code %A, sha256 4debc868e0be8e01…

27: PHASE FCC_A1 %A 2 1 1 !
28: CONST FCC_A1 : NP PU% : VA : !

HCP_A3 (Np–Pu)

Id: phase:np-pu:hcp-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
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:np-pu:hcp-a3
tdb: tdb:NpPu-10Kur.tdb:HCP_A3

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

NpPu-10Kur.tdb: HCP_A3, type code %A, sha256 4debc868e0be8e01…

37: PHASE HCP_A3 %A 2 1 0.5 !
38: CONST HCP_A3 : NP PU : VA : !

LIQUID (Np–Pu)

Id: phase:np-pu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 831.62–4000 K, x(Pu) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:liquid
tdb: tdb:NpPu-10Kur.tdb:LIQUID

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

NpPu-10Kur.tdb: LIQUID, type code %, sha256 4debc868e0be8e01…

22: PHASE LIQUID:L % 1 1 !
23: CONST LIQUID:L : NP PU : !

NPPU_ETA (Np–Pu)

Id: phase:np-pu:nppu-eta; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model
Candidate (sgte_mmc2): (NpPu-eta) · tP52 — Hallstedt 2025 mmc2 row for NPPU_ETA: NpPu-eta
Stability: stable in 1 of 1 calculated diagram(s): 554.55–776.31 K, x(Pu) 0.52046–0.97329
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:nppu-eta
tdb: tdb:NpPu-10Kur.tdb:NPPU_ETA

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

NpPu-10Kur.tdb: NPPU_ETA, type code %, sha256 4debc868e0be8e01…

72: PHASE NPPU_ETA % 1 1 !
73: CONST NPPU_ETA : NP PU : !

ORTHO_AC (Np–Pu)

Id: phase:np-pu:ortho-ac; status assigned
Structure: alpha-Np · A_c · oP8 · Pnma (62); type st:a-c-alpha-np-op8; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–555.02 K, x(Pu) 0–0.05172
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:ortho-ac
tdb: tdb:NpPu-10Kur.tdb:ORTHO_AC

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

NpPu-10Kur.tdb: ORTHO_AC, type code %, sha256 4debc868e0be8e01…

47: PHASE ORTHO_AC % 1 1 !
48: CONST ORTHO_AC : NP% PU : !

ALPHA_PU (Np–Pu)

Id: phase:np-pu:pu-alpha; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model
Candidate (sgte_mmc2): alpha-Pu · mP16 · P2_1/m (11) — Hallstedt 2025 mmc2 row for ALPHA_PU: Pu (alpha)
Candidate (tdb_comment): alpha-Pu · mP16 · P2_1/m — NpPu-10Kur.tdb: 'Prototype alpha-Pu (mP16, P2_1/m)'
Stability: stable in 1 of 1 calculated diagram(s): 300–572.02 K, x(Pu) 0.08645–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:pu-alpha
tdb: tdb:NpPu-10Kur.tdb:ALPHA_PU

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

NpPu-10Kur.tdb: ALPHA_PU, type code %, sha256 4debc868e0be8e01…

57: PHASE ALPHA_PU % 1 1 !
58: CONST ALPHA_PU : NP PU% : !

BETA_PU (Np–Pu)

Id: phase:np-pu:pu-beta; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model
Candidate (sgte_mmc2): beta-Pu · mC34 · C2/m (12) — Hallstedt 2025 mmc2 row for BETA_PU: Pu (beta)
Candidate (tdb_comment): beta-Pu · mC34 · C2/m — NpPu-10Kur.tdb: 'Prototype beta-Pu (mC34, C2/m)'
Stability: stable in 1 of 1 calculated diagram(s): 397.62–820.42 K, x(Pu) 0.20885–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:pu-beta
tdb: tdb:NpPu-10Kur.tdb:BETA_PU

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

NpPu-10Kur.tdb: BETA_PU, type code %, sha256 4debc868e0be8e01…

62: PHASE BETA_PU % 1 1 !
63: CONST BETA_PU : NP PU% : !

GAMMA_PU (Np–Pu)

Id: phase:np-pu:pu-gamma; status needs_review
No structure assigned. Why: no_structure_token; off_stoichiometric_model
Candidate (sgte_mmc2): gamma-Pu · oF8 · Fddd (70) — Hallstedt 2025 mmc2 row for GAMMA_PU: Hg4In, Pu (gamma)
Candidate (tdb_comment): gamma-Pu · oF8 · Fddd — NpPu-10Kur.tdb: 'Prototype gamma-Pu (oF8, Fddd)'
Stability: stable in 1 of 1 calculated diagram(s): 402.91–599.83 K, x(Pu) 0.98334–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:np-pu:pu-gamma
tdb: tdb:NpPu-10Kur.tdb:GAMMA_PU

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

NpPu-10Kur.tdb: GAMMA_PU, type code %, sha256 4debc868e0be8e01…

67: PHASE GAMMA_PU % 1 1 !
68: CONST GAMMA_PU : NP PU% : !

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}
}