Cu–Pu phases

12 phases (tier A 4, tier C 2, liquid 1, needs_review 5); 11 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 · Cu–Pu system page · Markdown · field reference

Phases of the Cu–Pu system (12)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
TETRAGONAL_A6 phase:cu-pu:a6-tetragonal	In · A6 · tI2 · I4/mmm (139)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 700.79–755.67 K, x(Pu) 0.99888–1	4	1
BCC_A2 phase:cu-pu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 720–3999.25 K, x(Pu) 0.94026–1	4	1
CU17PU4 phase:cu-pu:cu17pu4		needs_review	stable in 1 of 1 calculated diagram(s): 300–1228.87 K, x(Pu) 0.19048–0.19048	4	1
CU2PU phase:cu-pu:cu2pu	Hg2K · oI12 · Imma (74)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1133.59 K, x(Pu) 0.33333–0.33333	8	1
CU4PU phase:cu-pu:cu4pu		needs_review	stable in 1 of 1 calculated diagram(s): 300–1173.87 K, x(Pu) 0.2–0.2	4	1
CU6PU phase:cu-pu:cu6pu	CeCu6 · oP28 · Pnma (62)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1203.82 K, x(Pu) 0.14286–0.14286	4	1
FCC_A1 phase:cu-pu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1443.38 K, x(Pu) 0–1	3	1
HCP_A3 phase:cu-pu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
LIQUID phase:cu-pu:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 899.88–4000 K, x(Pu) 0–1	10	1
ALPHA_PU phase:cu-pu:pu-alpha		needs_review	stable in 1 of 1 calculated diagram(s): 300–397.62 K, x(Pu) 1–1	0	1
BETA_PU phase:cu-pu:pu-beta		needs_review	stable in 1 of 1 calculated diagram(s): 397.62–487.9 K, x(Pu) 1–1	0	1
GAMMA_PU phase:cu-pu:pu-gamma		needs_review	stable in 1 of 1 calculated diagram(s): 487.9–593.06 K, x(Pu) 1–1	0	1

TETRAGONAL_A6 (Cu–Pu)

Id: phase:cu-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): 700.79–755.67 K, x(Pu) 0.99888–1
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:cu-pu:a6-tetragonal, corpus:phase:cu-pu:tetragonal-a6
paper: paper:10.1016/j.jnucmat.2009.04.017:δ'Pu
tdb: tdb:CuPu-09Wan.tdb:TETRAGONAL_A6

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

CuPu-09Wan.tdb: TETRAGONAL_A6, type code %, sha256 6d0db724a0d0d814…

41: PHASE TETRAGONAL_A6 % 1 1 !
42: CONST TETRAGONAL_A6 : CU PU% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

BCC_A2 (Cu–Pu)

Id: phase:cu-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): 720–3999.25 K, x(Pu) 0.94026–1
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:bcc-a2
paper: paper:10.1016/j.jnucmat.2009.04.017:εPu
tdb: tdb:CuPu-09Wan.tdb:BCC_A2

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

CuPu-09Wan.tdb: BCC_A2, type code %B, sha256 6d0db724a0d0d814…

31: PHASE BCC_A2 %B 2 1 3 !
32: CONST BCC_A2 : CU PU% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

CU17PU4 (Cu–Pu)

Id: phase:cu-pu:cu17pu4; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (literature_printed): (Cu17Pu4) · ? — printed with a label mapped to this phase
Candidate (sgte_mmc2): (Cu17Pu4) — Hallstedt 2025 mmc2 row for CU17PU4: Cu17Pu4
Stoichiometry: Cu 0.8095, Pu 0.1905
Stability: stable in 1 of 1 calculated diagram(s): 300–1228.87 K, x(Pu) 0.19048–0.19048
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:cu17pu4
paper: paper:10.1016/j.jnucmat.2009.04.017:Cu17Pu4
tdb: tdb:CuPu-09Wan.tdb:CU17PU4

TDB models of CU17PU4 (1): PHASE and CONSTITUENT statements as written

CuPu-09Wan.tdb: CU17PU4, type code %, sha256 6d0db724a0d0d814…

66: PHASE CU17PU4 % 2 17 4 !
67: CONST CU17PU4 : CU : PU : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

CU2PU (Cu–Pu)

Id: phase:cu-pu:cu2pu; status assigned
Structure: Hg2K · oI12 · Imma (74); type st:hg2k-oi12; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (no_on_hull_entry_in_oqmd, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Cu 0.6667, Pu 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1133.59 K, x(Pu) 0.33333–0.33333
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:cu2pu
paper: paper:10.1016/j.jnucmat.2009.04.017:Cu2Pu
tdb: tdb:CuPu-09Wan.tdb:CU2PU

TDB models of CU2PU (1): PHASE and CONSTITUENT statements as written

CuPu-09Wan.tdb: CU2PU, type code %, sha256 6d0db724a0d0d814…

76: PHASE CU2PU % 2 2 1 !
77: CONST CU2PU : CU : PU : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

CU4PU (Cu–Pu)

Id: phase:cu-pu:cu4pu; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (literature_printed): (Cu4Pu) · oP20 — printed with a label mapped to this phase
Candidate (sgte_mmc2): (Cu4Pu) · oP20 — Hallstedt 2025 mmc2 row for CU4PU: Cu4Pu
Stoichiometry: Cu 0.8000, Pu 0.2000
Stability: stable in 1 of 1 calculated diagram(s): 300–1173.87 K, x(Pu) 0.2–0.2
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:cu4pu
paper: paper:10.1016/j.jnucmat.2009.04.017:Cu4Pu
tdb: tdb:CuPu-09Wan.tdb:CU4PU

TDB models of CU4PU (1): PHASE and CONSTITUENT statements as written

CuPu-09Wan.tdb: CU4PU, type code %, sha256 6d0db724a0d0d814…

71: PHASE CU4PU % 2 4 1 !
72: CONST CU4PU : CU : PU : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

CU6PU (Cu–Pu)

Id: phase:cu-pu:cu6pu; status assigned
Structure: CeCu6 · oP28 · Pnma (62); type st:cecu6-op28; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (no_on_hull_entry_in_oqmd, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Cu 0.8571, Pu 0.1429
Stability: stable in 1 of 1 calculated diagram(s): 300–1203.82 K, x(Pu) 0.14286–0.14286
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:cu6pu
paper: paper:10.1016/j.jnucmat.2009.04.017:Cu6Pu
tdb: tdb:CuPu-09Wan.tdb:CU6PU

TDB models of CU6PU (1): PHASE and CONSTITUENT statements as written

CuPu-09Wan.tdb: CU6PU, type code %, sha256 6d0db724a0d0d814…

61: PHASE CU6PU % 2 6 1 !
62: CONST CU6PU : CU : PU : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

FCC_A1 (Cu–Pu)

Id: phase:cu-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): 300–1443.38 K, x(Pu) 0–1
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:cu-pu:fcc-a1
paper: paper:10.1016/j.jnucmat.2009.04.017:(Cu), paper:10.1016/j.jnucmat.2009.04.017:δPu
tdb: tdb:CuPu-09Wan.tdb:FCC_A1

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

CuPu-09Wan.tdb: FCC_A1, type code %A, sha256 6d0db724a0d0d814…

26: PHASE FCC_A1 %A 2 1 1 !
27: CONST FCC_A1 : CU% PU% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

HCP_A3 (Cu–Pu)

Id: phase:cu-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
Stoichiometry: Cu 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:cu-pu:hcp-a3
tdb: tdb:CuPu-09Wan.tdb:HCP_A3

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

CuPu-09Wan.tdb: HCP_A3, type code %A, sha256 6d0db724a0d0d814…

36: PHASE HCP_A3 %A 2 1 0.5 !
37: CONST HCP_A3 : CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase

LIQUID (Cu–Pu)

Id: phase:cu-pu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 899.88–4000 K, x(Pu) 0–1
Literature: 10 values (10 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:cu-pu:liquid
paper: paper:10.1016/j.jnucmat.2009.04.017:L
tdb: tdb:CuPu-09Wan.tdb:LIQUID

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

CuPu-09Wan.tdb: LIQUID, type code %, sha256 6d0db724a0d0d814…

21: PHASE LIQUID:L % 1 1 !
22: CONST LIQUID:L : CU PU : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase; reports values for this phase

ALPHA_PU (Cu–Pu)

Id: phase:cu-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 — CuPu-09Wan.tdb: 'Prototype alpha-Pu (mP16, P2_1/m)'
Stability: stable in 1 of 1 calculated diagram(s): 300–397.62 K, x(Pu) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:cu-pu:pu-alpha
tdb: tdb:CuPu-09Wan.tdb:ALPHA_PU

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

CuPu-09Wan.tdb: ALPHA_PU, type code %, sha256 6d0db724a0d0d814…

46: PHASE ALPHA_PU % 1 1 !
47: CONST ALPHA_PU : CU PU% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase

BETA_PU (Cu–Pu)

Id: phase:cu-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 — CuPu-09Wan.tdb: 'Prototype beta-Pu (mC34, C2/m)'
Stability: stable in 1 of 1 calculated diagram(s): 397.62–487.9 K, x(Pu) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:cu-pu:pu-beta
tdb: tdb:CuPu-09Wan.tdb:BETA_PU

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

CuPu-09Wan.tdb: BETA_PU, type code %, sha256 6d0db724a0d0d814…

51: PHASE BETA_PU % 1 1 !
52: CONST BETA_PU : CU PU% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
assessment that models this phase

GAMMA_PU (Cu–Pu)

Id: phase:cu-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 — CuPu-09Wan.tdb: 'Prototype gamma-Pu (oF8, Fddd)'
Stability: stable in 1 of 1 calculated diagram(s): 487.9–593.06 K, x(Pu) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:cu-pu:pu-gamma
tdb: tdb:CuPu-09Wan.tdb:GAMMA_PU

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

CuPu-09Wan.tdb: GAMMA_PU, type code %, sha256 6d0db724a0d0d814…

56: PHASE GAMMA_PU % 1 1 !
57: CONST GAMMA_PU : CU PU% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jnucmat.2009.04.017 C.P. Wang, W. Fang, Z.S. Li, X.J. Liu, Thermodynamic modeling of the Mg–Pu and Cu–Pu systems, Journal of Nuclear Materials 392, 525-530 (2009).
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}
}