Se–Tl phases

9 phases (tier A 5, tier C 1, liquid 1, needs_review 2); 8 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 · Se–Tl system page · Markdown · field reference

Phases of the Se–Tl system (9)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
HEXAGONAL_A8 phase:se-tl:a8-hexagonal	gamma-Se · A8 · hP3 · P3_121 (152)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–494 K, x(Se) 1–1	0	1
BCC_A2 phase:se-tl:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 507–2499.5 K, x(Se) 0–0	0	1
FCC_A1 phase:se-tl: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:se-tl:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–507 K, x(Se) 0–0	0	1
LIQUID phase:se-tl:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 475.38–2500 K, x(Se) 0–1	0	1
TL2SE phase:se-tl:tl2se		needs_review	stable in 1 of 1 calculated diagram(s): 300–519.76 K, x(Se) 0.33333–0.33333	1	1
TL5SE3 phase:se-tl:tl5se3	Tl5Se3 · tP32 · P4/n (85)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–653.07 K, x(Se) 0.33346–0.37218	0	1
TLSE_B37 phase:se-tl:tlse-b37	TlSe-alpha · B37 · tI16 · I4/mcm (140)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–465.66 K, x(Se) 0.5–0.5	0	1
TLSE_BETA phase:se-tl:tlse-beta		needs_review	stable in 1 of 1 calculated diagram(s): 465.66–618.36 K, x(Se) 0.5–0.5	0	1

HEXAGONAL_A8 (Se–Tl)

Id: phase:se-tl:a8-hexagonal; status assigned
Structure: gamma-Se · A8 · hP3 · P3_121 (152); type st:a8-gamma-se-hp3; tier A: standard phase name; confidence high
Stoichiometry: Se 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–494 K, x(Se) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:a8-hexagonal
tdb: tdb:TlSe-00Roe-LB.tdb:HEXAGONAL_A8

TDB models of HEXAGONAL_A8 (1): PHASE and CONSTITUENT statements as written

TlSe-00Roe-LB.tdb: HEXAGONAL_A8, type code %, sha256 8323ab45605996cf…

52: PHASE HEXAGONAL_A8 % 1 1 !
53: CONST HEXAGONAL_A8 : SE : !

BCC_A2 (Se–Tl)

Id: phase:se-tl:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stoichiometry: Tl 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 507–2499.5 K, x(Se) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:bcc-a2
tdb: tdb:TlSe-00Roe-LB.tdb:BCC_A2

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

TlSe-00Roe-LB.tdb: BCC_A2, type code %B, sha256 8323ab45605996cf…

42: PHASE BCC_A2 %B 2 1 3 !
43: CONST BCC_A2 : TL : VA : !

FCC_A1 (Se–Tl)

Id: phase:se-tl:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Tl 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:se-tl:fcc-a1
tdb: tdb:TlSe-00Roe-LB.tdb:FCC_A1

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

TlSe-00Roe-LB.tdb: FCC_A1, type code %A, sha256 8323ab45605996cf…

37: PHASE FCC_A1 %A 2 1 1 !
38: CONST FCC_A1 : TL : VA : !

HCP_A3 (Se–Tl)

Id: phase:se-tl: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: Tl 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–507 K, x(Se) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:hcp-a3
tdb: tdb:TlSe-00Roe-LB.tdb:HCP_A3

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

TlSe-00Roe-LB.tdb: HCP_A3, type code %A, sha256 8323ab45605996cf…

47: PHASE HCP_A3 %A 2 1 0.5 !
48: CONST HCP_A3 : TL : VA : !

LIQUID (Se–Tl)

Id: phase:se-tl:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 475.38–2500 K, x(Se) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:liquid
tdb: tdb:TlSe-00Roe-LB.tdb:LIQUID

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

TlSe-00Roe-LB.tdb: LIQUID, type code %, sha256 8323ab45605996cf…

32: PHASE LIQUID:L % 1 1 !
33: CONST LIQUID:L : SE TL TL2SE : !

TL2SE (Se–Tl)

Id: phase:se-tl:tl2se; status needs_review
No structure assigned. Why: no_on_hull_entry_in_mp; no_structure_token; sgte_mmc2_row_incomplete
Candidate (dft_oqmd): P3 (143) — on-hull OQMD Se1 Tl2 at x(TL)=0.6667
Candidate (sgte_mmc2): (Tl2Se) — Hallstedt 2025 mmc2 row for TL2SE: Tl2Se
Stoichiometry: Se 0.3333, Tl 0.6667
Stability: stable in 1 of 1 calculated diagram(s): 300–519.76 K, x(Se) 0.33333–0.33333
Literature: 1 values (1 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:se-tl:tl2se
paper: paper:10.1016/s0966-9795(99)00068-0:Tl2Se
tdb: tdb:TlSe-00Roe-LB.tdb:TL2SE

TDB models of TL2SE (1): PHASE and CONSTITUENT statements as written

TlSe-00Roe-LB.tdb: TL2SE, type code %, sha256 8323ab45605996cf…

57: PHASE TL2SE % 2 2 1 !
58: CONST TL2SE : TL : SE : !

Example references (1 of 1; assessments first):

doi:10.1016/s0966-9795(99)00068-0 F. Römermann, Y. Feutelais, S.G. Fries, R. Blachnik, Phase diagram experimental investigation and thermodynamic assessment of the thallium–selenium system, Intermetallics 8, 53-65 (2000).
reports values for this phase

TL5SE3 (Se–Tl)

Id: phase:se-tl:tl5se3; status assigned
Structure: Tl5Se3 · tP32 · P4/n (85); type st:tl5se3-tp32; 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_structure_token, off_stoichiometric_model); structure as stated in the SGTE crystallographic table for this phase name and system
Stability: stable in 1 of 1 calculated diagram(s): 300–653.07 K, x(Se) 0.33346–0.37218
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:tl5se3
tdb: tdb:TlSe-00Roe-LB.tdb:TL5SE3

TDB models of TL5SE3 (1): PHASE and CONSTITUENT statements as written

TlSe-00Roe-LB.tdb: TL5SE3, type code %, sha256 8323ab45605996cf…

62: PHASE TL5SE3 % 3 5 2 1 !
63: CONST TL5SE3 : TL : SE : SE TL : !

TLSE_B37 (Se–Tl)

Id: phase:se-tl:tlse-b37; status assigned
Structure: TlSe-alpha · B37 · tI16 · I4/mcm (140); type st:b37-tlse-alpha-ti16; tier A: standard phase name; confidence high
Stoichiometry: Se 0.5000, Tl 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–465.66 K, x(Se) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:tlse-b37
tdb: tdb:TlSe-00Roe-LB.tdb:TLSE_B37

TDB models of TLSE_B37 (1): PHASE and CONSTITUENT statements as written

TlSe-00Roe-LB.tdb: TLSE_B37, type code %, sha256 8323ab45605996cf…

67: PHASE TLSE_B37 % 2 1 1 !
68: CONST TLSE_B37 : TL : SE : !

TLSE_BETA (Se–Tl)

Id: phase:se-tl:tlse-beta; status needs_review
No structure assigned. Why: no_structure_token; polymorph_family:other phases of this system have the same composition
Candidate (dft_mp): I4/mcm (140) — on-hull MP TlSe at x(TL)=0.5000
Candidate (sgte_mmc2): (TlSe-beta) — Hallstedt 2025 mmc2 row for TLSE_BETA: TlSe-beta
Stoichiometry: Se 0.5000, Tl 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 465.66–618.36 K, x(Se) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:se-tl:tlse-beta
tdb: tdb:TlSe-00Roe-LB.tdb:TLSE_BETA

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

TlSe-00Roe-LB.tdb: TLSE_BETA, type code %, sha256 8323ab45605996cf…

72: PHASE TLSE_BETA % 2 1 1 !
73: CONST TLSE_BETA : TL : SE : !

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}
}