Bi–Cs phases

9 phases (tier A 6, tier C 1, liquid 1, needs_review 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 · Bi–Cs system page · Markdown · field reference

Phases of the Bi–Cs system (9)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
RHOMBOHEDRAL_A7 phase:bi-cs:a7-rhombohedral	alpha-As · A7 · hR2 · R-3m (166)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–544.55 K, x(Cs) 0–0	4	1
BCC_A2 phase:bi-cs:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–301.5 K, x(Cs) 1–1	2	1
BI2CS_C15 phase:bi-cs:bi2cs-c15	Cu2Mg · C15 · cF24 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–854.13 K, x(Cs) 0.33333–0.33333	11	1
BI2CS3 phase:bi-cs:bi2cs3	Eu3Ga2 · mC20 · C2/c (15)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–760 K, x(Cs) 0.6–0.6	21	1
BI4CS5 phase:bi-cs:bi4cs5		needs_review	stable in 1 of 1 calculated diagram(s): 300–679.55 K, x(Cs) 0.55556–0.55556	14	1
BICS3_D03 phase:bi-cs:bics3-d03	BiF3 · D0_3 · cF16 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–934.18 K, x(Cs) 0.75–0.75	10	1
FCC_A1 phase:bi-cs:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
HCP_A3 phase:bi-cs: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:bi-cs:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 301.5–2500 K, x(Cs) 0–1	24	1

RHOMBOHEDRAL_A7 (Bi–Cs)

Id: phase:bi-cs:a7-rhombohedral; status assigned
Structure: alpha-As · A7 · hR2 · R-3m (166); type st:a7-alpha-as-hr2; tier A: standard phase name; confidence high
Stoichiometry: Bi 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–544.55 K, x(Cs) 0–0
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:bi-cs:a7-rhombohedral, corpus:phase:bi-cs:rhombohedral-a7
paper: paper:10.1016/j.calphad.2014.11.002:(Bi)
tdb: tdb:BiCs-15Dja.tdb:RHOMBOHEDRAL_A7

TDB models of RHOMBOHEDRAL_A7 (1): PHASE and CONSTITUENT statements as written

BiCs-15Dja.tdb: RHOMBOHEDRAL_A7, type code %, sha256 f0497ab1e5628a60…

47: PHASE RHOMBOHEDRAL_A7 % 1 1 !
48: CONST RHOMBOHEDRAL_A7 : BI : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
cited as the source of values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase

BCC_A2 (Bi–Cs)

Id: phase:bi-cs: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): 300–301.5 K, x(Cs) 1–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:bi-cs:bcc-a2
paper: paper:10.1016/j.calphad.2014.11.002:(Cs)
tdb: tdb:BiCs-15Dja.tdb:BCC_A2

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

BiCs-15Dja.tdb: BCC_A2, type code %B, sha256 f0497ab1e5628a60…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : BI CS% : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase

BI2CS_C15 (Bi–Cs)

Id: phase:bi-cs:bi2cs-c15; status assigned
Structure: Cu2Mg · C15 · cF24 · Fd-3m (227); type st:c15-cu2mg-cf24; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaabigx and oqmd-647553, space group 227
Stoichiometry: Bi 0.6667, Cs 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–854.13 K, x(Cs) 0.33333–0.33333
Literature: 11 values (11 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:bi-cs:bi2cs-c15
mp: mp:mp-aaaabigx
oqmd: oqmd:oqmd-647553
paper: paper:10.1016/j.calphad.2014.11.002:Bi2Cs
tdb: tdb:BiCs-15Dja.tdb:BI2CS_C15

TDB models of BI2CS_C15 (1): PHASE and CONSTITUENT statements as written

BiCs-15Dja.tdb: BI2CS_C15, type code %, sha256 f0497ab1e5628a60…

52: PHASE BI2CS_C15 % 2 2 1 !
53: CONST BI2CS_C15 : BI : CS : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
cited as the source of values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase

BI2CS3 (Bi–Cs)

Id: phase:bi-cs:bi2cs3; status assigned
Structure: Eu3Ga2 · mC20 · C2/c (15); type st:eu3ga2-mc20; 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_both, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Bi 0.4000, Cs 0.6000
Stability: stable in 1 of 1 calculated diagram(s): 300–760 K, x(Cs) 0.6–0.6
Literature: 21 values (21 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:bi-cs:bi2cs3
paper: paper:10.1016/j.calphad.2014.11.002:Bi2Cs3
tdb: tdb:BiCs-15Dja.tdb:BI2CS3

TDB models of BI2CS3 (1): PHASE and CONSTITUENT statements as written

BiCs-15Dja.tdb: BI2CS3, type code %, sha256 f0497ab1e5628a60…

62: PHASE BI2CS3 % 2 2 3 !
63: CONST BI2CS3 : BI : CS : !

Example references (4 of 4; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase
doi:10.1021/ja002606t Franck Gascoin, Slavi C. Sevov, Synthesis and Characterization of A3Bi2 (A = K, Rb, Cs) with Isolated Diatomic Dianion of Bismuth, [Bi2]2-, and an Extra Delocalized Electron, J. Am. Chem. Soc. 122, 10251-10252 (2000).
cited as the source of values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
cited as the source of values for this phase

BI4CS5 (Bi–Cs)

Id: phase:bi-cs:bi4cs5; status needs_review
No structure assigned. Why: assessment_declared_compound_differs_from_model_composition; no_on_hull_entry_in_mp; no_structure_token
Candidate (dft_oqmd): C2/m (12) — on-hull OQMD Bi4 Cs5 at x(CS)=0.5556
Candidate (literature_printed): Rb5As4 · mC20 — printed with a label mapped to this phase
Candidate (sgte_mmc2): Rb5As4 · mC20 · C2/m (12) — Hallstedt 2025 mmc2 row for BI4CS5: Bi24Cs5
Candidate (tdb_comment): Rb5As4 · mC20 · C2/m — BiCs-15Dja.tdb: 'Prototype Rb5As4 (mC20, C2/m)'
Stoichiometry: Bi 0.4444, Cs 0.5556
Stability: stable in 1 of 1 calculated diagram(s): 300–679.55 K, x(Cs) 0.55556–0.55556
Literature: 14 values (14 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:bi-cs:bi4cs5
paper: paper:10.1016/j.calphad.2014.11.002:Bi4Cs5
tdb: tdb:BiCs-15Dja.tdb:BI4CS5

TDB models of BI4CS5 (1): PHASE and CONSTITUENT statements as written

BiCs-15Dja.tdb: BI4CS5, type code %, sha256 f0497ab1e5628a60…

57: PHASE BI4CS5 % 2 4 5 !
58: CONST BI4CS5 : BI : CS : !

Example references (4 of 4; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1021/ic0104499 Franck Gascoin, Slavi C. Sevov, Synthesis and Characterization of the “Metallic Salts” A5Pn4 (A = K, Rb, Cs and Pn = As, Sb, Bi) with Isolated Zigzag Tetramers of Pn44- and an Extra Delocalized Electron, Inorg. Chem. 40, 5177-5181 (2001).
cited as the source of values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
cited as the source of values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase

BICS3_D03 (Bi–Cs)

Id: phase:bi-cs:bics3-d03; status assigned
Structure: BiF3 · D0_3 · cF16 · Fm-3m (225); type st:d0-3-bif3-cf16; tier A: standard phase name; confidence high
Stoichiometry: Bi 0.2500, Cs 0.7500
Stability: stable in 1 of 1 calculated diagram(s): 300–934.18 K, x(Cs) 0.75–0.75
Literature: 10 values (10 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:bi-cs:bics3-d03
paper: paper:10.1016/j.calphad.2014.11.002:BiCs3
tdb: tdb:BiCs-15Dja.tdb:BICS3_D03

TDB models of BICS3_D03 (1): PHASE and CONSTITUENT statements as written

BiCs-15Dja.tdb: BICS3_D03, type code %, sha256 f0497ab1e5628a60…

67: PHASE BICS3_D03 % 2 1 3 !
68: CONST BICS3_D03 : BI : CS : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
cited as the source of values for this phase

FCC_A1 (Bi–Cs)

Id: phase:bi-cs:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; 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:bi-cs:fcc-a1
tdb: tdb:BiCs-15Dja.tdb:FCC_A1

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

BiCs-15Dja.tdb: FCC_A1, type code %A, sha256 f0497ab1e5628a60…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : BI CS : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase

HCP_A3 (Bi–Cs)

Id: phase:bi-cs: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:bi-cs:hcp-a3
tdb: tdb:BiCs-15Dja.tdb:HCP_A3

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

BiCs-15Dja.tdb: HCP_A3, type code %A, sha256 f0497ab1e5628a60…

42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : BI CS : VA: !

Example references (1 of 1; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase

LIQUID (Bi–Cs)

Id: phase:bi-cs:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 301.5–2500 K, x(Cs) 0–1
Literature: 24 values (24 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:bi-cs:liquid
paper: paper:10.1016/j.calphad.2014.11.002:L
tdb: tdb:BiCs-15Dja.tdb:LIQUID

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

BiCs-15Dja.tdb: LIQUID, type code %, sha256 f0497ab1e5628a60…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : BI BICS BICS3 CS : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2014.11.002 Y. Djaballah, A. Said Amer, Ş. Uğur, G. Uğur, A. Hidoussi, A. Belgacem-Bouzida, Thermodynamic description of the Bi–Cs and Bi–Tm system supported by first-principles calculations, Calphad 48, 72-78 (2015).
assessment that models this phase; reports values for this phase
doi:10.1007/bf02645965 J. Sangster, A. Pelton, The Bi–Cs (bismuth–cesium) system, J. Phase Equilib. 12 (1991) 443–446.
cited as the source of values for this phase
doi:10.1002/zaac.19613090305 Geert Gnutzmann, Wilhelm Klemm, Das Verhalten der Alkalimetalle zu Halbmetallen. IV. Die Systeme des Kaliums, Rubidiums und Caesiums mit Wismut, Zeitschrift anorg allge chemie 309, 181-188 (1961).
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}
}