Fe–Np phases

8 phases (tier A 7, liquid 1); 7 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 · Fe–Np system page · Markdown · field reference

Phases of the Fe–Np system (8)
Phase	Structure	Basis	Stability (calculated)	TDB models
TETRAG_AD phase:fe-np:ad-tetrag	beta-Np · A_d · tP4 · P4/nmm (129)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 555.03–910.95 K, x(Np) 0.99657–1	1
BCC_A2 phase:fe-np:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1811.94 K, x(Np) 0–1	1
FCC_A1 phase:fe-np:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1174.23–1674.35 K, x(Np) 0–0.01552	1
FE2NP_C15 phase:fe-np:fe2np-c15	Cu2Mg · C15 · cF24 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1503.73 K, x(Np) 0.33333–0.33333	1
FENP6_D2C phase:fe-np:fenp6-d2c	MnU6 · D2_c · tI28 · I4/mcm (140)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–810.38 K, x(Np) 0.85714–0.85714	1
HCP_A3 phase:fe-np:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
LIQUID phase:fe-np:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 802.42–2500 K, x(Np) 0–1	1
ORTHO_AC phase:fe-np:ortho-ac	alpha-Np · A_c · oP8 · Pnma (62)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–555.03 K, x(Np) 0.99999–1	1

TETRAG_AD (Fe–Np)

Id: phase:fe-np: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): 555.03–910.95 K, x(Np) 0.99657–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

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

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

FeNp-10Kur.tdb: TETRAG_AD, type code %, sha256 3deacdb9f4c0dc75…

45: PHASE TETRAG_AD % 1 1 !
46: CONST TETRAG_AD : FE NP% : !

BCC_A2 (Fe–Np)

Id: phase:fe-np: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): 300–1811.94 K, x(Np) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

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

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

FeNp-10Kur.tdb: BCC_A2, type code %B, sha256 3deacdb9f4c0dc75…

30: PHASE BCC_A2 %B 2 1 3 !
31: CONST BCC_A2 : FE% NP% : VA : !

FCC_A1 (Fe–Np)

Id: phase:fe-np: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): 1174.23–1674.35 K, x(Np) 0–0.01552
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

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

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

FeNp-10Kur.tdb: FCC_A1, type code %A, sha256 3deacdb9f4c0dc75…

25: PHASE FCC_A1 %A 2 1 1 !
26: CONST FCC_A1 : FE% NP : VA : !

FE2NP_C15 (Fe–Np)

Id: phase:fe-np:fe2np-c15; status assigned
Structure: Cu2Mg · C15 · cF24 · Fd-3m (227); type st:c15-cu2mg-cf24; tier A: standard phase name; confidence high
Stoichiometry: Fe 0.6667, Np 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1503.73 K, x(Np) 0.33333–0.33333
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-np:fe2np-c15
tdb: tdb:FeNp-10Kur.tdb:FE2NP_C15

TDB models of FE2NP_C15 (1): PHASE and CONSTITUENT statements as written

FeNp-10Kur.tdb: FE2NP_C15, type code %, sha256 3deacdb9f4c0dc75…

50: PHASE FE2NP_C15 % 2 2 1 !
51: CONST FE2NP_C15 : FE : NP : !

FENP6_D2C (Fe–Np)

Id: phase:fe-np:fenp6-d2c; status assigned
Structure: MnU6 · D2_c · tI28 · I4/mcm (140); type st:d2-c-mnu6-ti28; tier A: standard phase name; confidence high
Stoichiometry: Fe 0.1429, Np 0.8571
Stability: stable in 1 of 1 calculated diagram(s): 300–810.38 K, x(Np) 0.85714–0.85714
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-np:fenp6-d2c
tdb: tdb:FeNp-10Kur.tdb:FENP6_D2C

TDB models of FENP6_D2C (1): PHASE and CONSTITUENT statements as written

FeNp-10Kur.tdb: FENP6_D2C, type code %, sha256 3deacdb9f4c0dc75…

55: PHASE FENP6_D2C % 2 1 6 !
56: CONST FENP6_D2C : FE : NP : !

HCP_A3 (Fe–Np)

Id: phase:fe-np: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:fe-np:hcp-a3
tdb: tdb:FeNp-10Kur.tdb:HCP_A3

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

FeNp-10Kur.tdb: HCP_A3, type code %A, sha256 3deacdb9f4c0dc75…

35: PHASE HCP_A3 %A 2 1 0.5 !
36: CONST HCP_A3 : FE NP : VA : !

LIQUID (Fe–Np)

Id: phase:fe-np:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 802.42–2500 K, x(Np) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-np:liquid
tdb: tdb:FeNp-10Kur.tdb:LIQUID

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

FeNp-10Kur.tdb: LIQUID, type code %, sha256 3deacdb9f4c0dc75…

20: PHASE LIQUID:L % 1 1 !
21: CONST LIQUID:L : FE NP : !

ORTHO_AC (Fe–Np)

Id: phase:fe-np: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): 300–555.03 K, x(Np) 0.99999–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

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

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

FeNp-10Kur.tdb: ORTHO_AC, type code %, sha256 3deacdb9f4c0dc75…

40: PHASE ORTHO_AC % 1 1 !
41: CONST ORTHO_AC : FE NP% : !

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}
}