F–K phases

7 phases (tier A 4, liquid 2, gas 1); 4 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 · F–K system page · Markdown · field reference

Phases of the F–K system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:f-k:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–336.52 K, x(F) 0–0	1	1
FCC_A1 phase:f-k:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
GAS phase:f-k:gas	gas	gas	stable in 1 of 1 calculated diagram(s): 300–2500 K, x(F) 0–1	2	1
HCP_A3 phase:f-k:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
ION phase:f-k:ion	liquid	liquid	stable in 1 of 1 calculated diagram(s): 336.52–1858.29 K, x(F) 0–0.5	0	1
KF_B1 phase:f-k:kf-b1	NaCl · B1 · cF8 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1131 K, x(F) 0.5–0.5	5	1
LIQUID phase:f-k:liquid	liquid	liquid	not stable in 1 calculated diagram(s)	6	1

BCC_A2 (F–K)

Id: phase:f-k:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: K 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–336.52 K, x(F) 0–0
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:f-k:bcc-a2
paper: paper:10.1016/j.msea.2005.11.037:bcc
tdb: tdb:KF-06Zha.tdb:BCC_A2

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

KF-06Zha.tdb: BCC_A2, type code %B, sha256 07ca7dab8fb54d1b…

44: PHASE BCC_A2 %B 2 1 3 !
45: CONST BCC_A2 : K : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase; reports values for this phase

FCC_A1 (F–K)

Id: phase:f-k:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: K 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:f-k:fcc-a1
tdb: tdb:KF-06Zha.tdb:FCC_A1

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

KF-06Zha.tdb: FCC_A1, type code %A, sha256 07ca7dab8fb54d1b…

39: PHASE FCC_A1 %A 2 1 1 !
40: CONST FCC_A1 : K : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase

GAS (F–K)

Id: phase:f-k:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–2500 K, x(F) 0–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:f-k:gas
paper: paper:10.1016/j.msea.2005.11.037:Gas (P = 3 bar)
tdb: tdb:KF-06Zha.tdb:GAS

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

KF-06Zha.tdb: GAS, type code %, sha256 07ca7dab8fb54d1b…

57: PHASE GAS:G % 1 1 !
58: CONST GAS:G : F F2 K K2 KF K2F2 : !

Example references (1 of 1; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase; reports values for this phase

HCP_A3 (F–K)

Id: phase:f-k: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: K 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:f-k:hcp-a3
tdb: tdb:KF-06Zha.tdb:HCP_A3

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

KF-06Zha.tdb: HCP_A3, type code %A, sha256 07ca7dab8fb54d1b…

49: PHASE HCP_A3 %A 2 1 0.5 !
50: CONST HCP_A3 : K : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase

ION (F–K)

Id: phase:f-k:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 336.52–1858.29 K, x(F) 0–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:f-k:ion
tdb: tdb:KF-06Zha.tdb:ION

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

KF-06Zha.tdb: ION, type code %, sha256 07ca7dab8fb54d1b…

31: PHASE ION:Y % 2 1 1 !
32: CONST ION:Y : K+1 : F-1 VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase

KF_B1 (F–K)

Id: phase:f-k:kf-b1; status assigned
Structure: NaCl · B1 · cF8 · Fm-3m (225); type st:b1-nacl-cf8; tier A: standard phase name; confidence high
Stoichiometry: F 0.5000, K 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–1131 K, x(F) 0.5–0.5
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:f-k:kf-b1
paper: paper:10.1016/j.msea.2005.11.037:KF
tdb: tdb:KF-06Zha.tdb:KF_B1

TDB models of KF_B1 (1): PHASE and CONSTITUENT statements as written

KF-06Zha.tdb: KF_B1, type code %, sha256 07ca7dab8fb54d1b…

54: PHASE KF_B1 % 2 1 1 !
55: CONST KF_B1 : K : F : !

Example references (2 of 2; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase; reports values for this phase
doi:10.1021/ja01607a016 M. A. Bredig, J. W. Johnson, Wm. T. Smith, Miscibility of Liquid Metals with Salts. I. The Sodium-Sodium Halide Systems<sup>1</sup>, J. Am. Chem. Soc. 77, 307-312 (1955).
cited as the source of values for this phase

LIQUID (F–K)

Id: phase:f-k:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stoichiometry: K 1.0000
Stability: not stable in 1 calculated diagram(s)
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (6): corpus: corpus:phase:f-k:liquid
paper: paper:10.1016/j.msea.2005.11.037:Liquid, paper:10.1016/j.msea.2005.11.037:Liquid 1, paper:10.1016/j.msea.2005.11.037:liquid, paper:10.1016/j.msea.2005.11.037:liquid 2
tdb: tdb:KF-06Zha.tdb:LIQUID

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

KF-06Zha.tdb: LIQUID, type code %, sha256 07ca7dab8fb54d1b…

34: PHASE LIQUID:L % 1 1 !
35: CONST LIQUID:L : K : !

Example references (2 of 2; assessments first):

doi:10.1016/j.msea.2005.11.037 Shengjun Zhang, Carl Brubaker, Chao Jiang, Mei Yang, Yu Zhong, Qingyou Han et al., A combined first-principles calculation and thermodynamic modeling of the F–K–Na system, Materials Science and Engineering: A 418, 161-171 (2006).
assessment that models this phase; reports values for this phase
doi:10.1021/ja01607a016 M. A. Bredig, J. W. Johnson, Wm. T. Smith, Miscibility of Liquid Metals with Salts. I. The Sodium-Sodium Halide Systems<sup>1</sup>, J. Am. Chem. Soc. 77, 307-312 (1955).
cited as the source of values for 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}
}