Pt–Ta phases

9 phases (tier A 4, tier C 2, 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 · Pt–Ta system page · Markdown · field reference

Phases of the Pt–Ta system (9)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:pt-ta:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–4000 K, x(Ta) 0.92704–1	1
FCC_A1 phase:pt-ta:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2044.7 K, x(Ta) 0–0.00013	1
HCP_A3 phase:pt-ta:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
LIQUID phase:pt-ta:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1944.7–4000 K, x(Ta) 0–1	1
PT2TA phase:pt-ta:pt2ta	Au2V · oC12 · Cmcm (63)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–2504.51 K, x(Ta) 0.33333–0.33333	1
PT3TA phase:pt-ta:pt3ta	NbPt3 · mP16 · P2_1/m (11)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–2520.53 K, x(Ta) 0.25–0.25	1
PTTA phase:pt-ta:ptta		needs_review	stable in 1 of 1 calculated diagram(s): 1909.6–2117.81 K, x(Ta) 0.5–0.5	1
PTTA3_D8B phase:pt-ta:ptta3-d8b	sigma-CrFe · D8_b · tP30 · P4_2/mnm (136)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 461.76–2632.67 K, x(Ta) 0.64392–0.77362	1
PTTA6 phase:pt-ta:ptta6		needs_review	stable in 1 of 1 calculated diagram(s): 300–2000 K, x(Ta) 0.85714–0.85714	1

BCC_A2 (Pt–Ta)

Id: phase:pt-ta: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): 300–4000 K, x(Ta) 0.92704–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:bcc-a2
tdb: tdb:PtTa-98Spe.tdb:BCC_A2

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

PtTa-98Spe.tdb: BCC_A2, type code %B, sha256 fd7011b9e894274e…

36: PHASE BCC_A2 %B 2 1 3 !
37: CONST BCC_A2 : PT TA% : VA : !

FCC_A1 (Pt–Ta)

Id: phase:pt-ta: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): 300–2044.7 K, x(Ta) 0–0.00013
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:fcc-a1
tdb: tdb:PtTa-98Spe.tdb:FCC_A1

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

PtTa-98Spe.tdb: FCC_A1, type code %A, sha256 fd7011b9e894274e…

31: PHASE FCC_A1 %A 2 1 1 !
32: CONST FCC_A1 : PT% TA : VA : !

HCP_A3 (Pt–Ta)

Id: phase:pt-ta: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:pt-ta:hcp-a3
tdb: tdb:PtTa-98Spe.tdb:HCP_A3

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

PtTa-98Spe.tdb: HCP_A3, type code %A, sha256 fd7011b9e894274e…

41: PHASE HCP_A3 %A 2 1 0.5 !
42: CONST HCP_A3 : PT TA : VA : !

LIQUID (Pt–Ta)

Id: phase:pt-ta:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1944.7–4000 K, x(Ta) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:liquid
tdb: tdb:PtTa-98Spe.tdb:LIQUID

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

PtTa-98Spe.tdb: LIQUID, type code %, sha256 fd7011b9e894274e…

26: PHASE LIQUID:L % 1 1 !
27: CONST LIQUID:L : PT TA : !

PT2TA (Pt–Ta)

Id: phase:pt-ta:pt2ta; status assigned
Structure: Au2V · oC12 · Cmcm (63); type st:au2v-oc12; 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 (dft_space_group_63_matches_3_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Pt 0.6667, Ta 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–2504.51 K, x(Ta) 0.33333–0.33333
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:pt2ta
tdb: tdb:PtTa-98Spe.tdb:PT2TA

TDB models of PT2TA (1): PHASE and CONSTITUENT statements as written

PtTa-98Spe.tdb: PT2TA, type code %, sha256 fd7011b9e894274e…

51: PHASE PT2TA % 2 2 1 !
52: CONST PT2TA : PT : TA : !

PT3TA (Pt–Ta)

Id: phase:pt-ta:pt3ta; status assigned
Structure: NbPt3 · mP16 · P2_1/m (11); type st:nbpt3-mp16; 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 (dft_space_group_11_matches_0_structure_types, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Pt 0.7500, Ta 0.2500
Stability: stable in 1 of 1 calculated diagram(s): 300–2520.53 K, x(Ta) 0.25–0.25
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:pt3ta
tdb: tdb:PtTa-98Spe.tdb:PT3TA

TDB models of PT3TA (1): PHASE and CONSTITUENT statements as written

PtTa-98Spe.tdb: PT3TA, type code %, sha256 fd7011b9e894274e…

46: PHASE PT3TA % 2 3 1 !
47: CONST PT3TA : PT : TA : !

PTTA (Pt–Ta)

Id: phase:pt-ta:ptta; status needs_review
No structure assigned. Why: no_on_hull_entry_in_mp; no_structure_token; sgte_mmc2_row_incomplete
Candidate (dft_oqmd): Pmma (51) — on-hull OQMD Pt1 Ta1 at x(TA)=0.5000
Candidate (sgte_mmc2): (PtTa) · tI2 — Hallstedt 2025 mmc2 row for PTTA: PtTa
Stoichiometry: Pt 0.5000, Ta 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 1909.6–2117.81 K, x(Ta) 0.5–0.5
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:ptta
tdb: tdb:PtTa-98Spe.tdb:PTTA

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

PtTa-98Spe.tdb: PTTA, type code %, sha256 fd7011b9e894274e…

56: PHASE PTTA % 2 1 1 !
57: CONST PTTA : PT : TA : !

PTTA3_D8B (Pt–Ta)

Id: phase:pt-ta:ptta3-d8b; status assigned
Structure: sigma-CrFe · D8_b · tP30 · P4_2/mnm (136); type st:d8-b-sigma-crfe-tp30; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 461.76–2632.67 K, x(Ta) 0.64392–0.77362
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:ptta3-d8b
tdb: tdb:PtTa-98Spe.tdb:PTTA3_D8B

TDB models of PTTA3_D8B (1): PHASE and CONSTITUENT statements as written

PtTa-98Spe.tdb: PTTA3_D8B, type code %, sha256 fd7011b9e894274e…

61: PHASE PTTA3_D8B % 1 1 !
62: CONST PTTA3_D8B : PT TA : !

PTTA6 (Pt–Ta)

Id: phase:pt-ta:ptta6; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (sgte_mmc2): (PtTa6) — Hallstedt 2025 mmc2 row for PTTA6: PtTa6
Stoichiometry: Pt 0.1429, Ta 0.8571
Stability: stable in 1 of 1 calculated diagram(s): 300–2000 K, x(Ta) 0.85714–0.85714
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pt-ta:ptta6
tdb: tdb:PtTa-98Spe.tdb:PTTA6

TDB models of PTTA6 (1): PHASE and CONSTITUENT statements as written

PtTa-98Spe.tdb: PTTA6, type code %, sha256 fd7011b9e894274e…

66: PHASE PTTA6 % 2 1 6 !
67: CONST PTTA6 : PT : TA : !

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}
}