Pr–Si phases

12 phases (tier A 7, tier C 3, liquid 1, needs_review 1); 10 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 · Pr–Si system page · Markdown · field reference

Phases of the Pr–Si system (12)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
DIAMOND_A4 phase:pr-si:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1687 K, x(Si) 1–1	0	1
BCC_A2 phase:pr-si:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1063.88–1208.88 K, x(Si) 0–0.00135	0	1
DHCP phase:pr-si:dhcp-a3	alpha-La · A3' · hP4 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1136.75 K, x(Si) 0–0	0	1
FCC_A1 phase:pr-si: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:pr-si: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:pr-si:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1003.93–2500 K, x(Si) 0–1	0	1
PR3SI4 phase:pr-si:pr3si4	V2B3 · oC20 · Cmcm (63)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1618.25 K, x(Si) 0.57143–0.57143	10	1
PR5SI3_D8L phase:pr-si:pr5si3-d8l	Cr5B3 · D8_l · tI32 · I4/mcm (140)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1670.8 K, x(Si) 0.375–0.375	0	1
PR5SI4 phase:pr-si:pr5si4	Si4Zr5 · tP36 · P4_12_12 (92)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1795.19 K, x(Si) 0.44444–0.44444	5	1
PR5SI9_ALPHA phase:pr-si:pr5si9-alpha	Gd5Si4 · oP36 · Pnma (62)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–305.34 K, x(Si) 0.64286–0.64286	0	1
PR5SI9_CC phase:pr-si:pr5si9-cc		needs_review	stable in 1 of 1 calculated diagram(s): 305.34–1972.55 K, x(Si) 0.64286–0.64286	3	1
PRSI_B27 phase:pr-si:prsi-b27	FeB · B27 · oP8 · Pnma (62)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1933.48 K, x(Si) 0.5–0.5	3	1

DIAMOND_A4 (Pr–Si)

Id: phase:pr-si:a4-diamond; status assigned
Structure: C (diamond) · A4 · cF8 · Fd-3m (227); type st:a4-c-diamond-cf8; tier A: standard phase name; confidence high
Stoichiometry: Si 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–1687 K, x(Si) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:a4-diamond
tdb: tdb:PrSi-20Xu.tdb:DIAMOND_A4

TDB models of DIAMOND_A4 (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: DIAMOND_A4, type code %, sha256 5164e34ad4f5ccca…

45: PHASE DIAMOND_A4 % 1 1 !
46: CONST DIAMOND_A4 : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

BCC_A2 (Pr–Si)

Id: phase:pr-si: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): 1063.88–1208.88 K, x(Si) 0–0.00135
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:bcc-a2
tdb: tdb:PrSi-20Xu.tdb:BCC_A2

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

PrSi-20Xu.tdb: BCC_A2, type code %B, sha256 5164e34ad4f5ccca…

30: PHASE BCC_A2 %B 2 1 3 !
31: CONST BCC_A2 : PR% SI : VA : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

DHCP (Pr–Si)

Id: phase:pr-si:dhcp-a3; status assigned
Structure: alpha-La · A3' · hP4 · P6_3/mmc (194); type st:a3-alpha-la-hp4; tier A: standard phase name; confidence high
Stoichiometry: Pr 1.0000
Stability: stable in 1 of 1 calculated diagram(s): 300–1136.75 K, x(Si) 0–0
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:dhcp-a3
tdb: tdb:PrSi-20Xu.tdb:DHCP

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

PrSi-20Xu.tdb: DHCP, type code %, sha256 5164e34ad4f5ccca…

40: PHASE DHCP % 1 1 !
41: CONST DHCP : PR : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

FCC_A1 (Pr–Si)

Id: phase:pr-si:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Si 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:pr-si:fcc-a1
tdb: tdb:PrSi-20Xu.tdb:FCC_A1

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

PrSi-20Xu.tdb: FCC_A1, type code %A, sha256 5164e34ad4f5ccca…

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

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

HCP_A3 (Pr–Si)

Id: phase:pr-si: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: Si 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:pr-si:hcp-a3
tdb: tdb:PrSi-20Xu.tdb:HCP_A3

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

PrSi-20Xu.tdb: HCP_A3, type code %A, sha256 5164e34ad4f5ccca…

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

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

LIQUID (Pr–Si)

Id: phase:pr-si:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1003.93–2500 K, x(Si) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:liquid
tdb: tdb:PrSi-20Xu.tdb:LIQUID

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

PrSi-20Xu.tdb: LIQUID, type code %, sha256 5164e34ad4f5ccca…

20: PHASE LIQUID:L % 1 1 !
21: CONST LIQUID:L : PR SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

PR3SI4 (Pr–Si)

Id: phase:pr-si:pr3si4; status assigned
Structure: V2B3 · oC20 · Cmcm (63); type st:v2b3-oc20; 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: Pr 0.4286, Si 0.5714
Stability: stable in 1 of 1 calculated diagram(s): 300–1618.25 K, x(Si) 0.57143–0.57143
Literature: 10 values (10 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:pr-si:pr3si4
paper: paper:10.1111/jace.17031:Pr3Si4
tdb: tdb:PrSi-20Xu.tdb:PR3SI4

TDB models of PR3SI4 (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PR3SI4, type code %, sha256 5164e34ad4f5ccca…

65: PHASE PR3SI4 % 2 3 4 !
66: CONST PR3SI4 : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase; reports values for this phase

PR5SI3_D8L (Pr–Si)

Id: phase:pr-si:pr5si3-d8l; status assigned
Structure: Cr5B3 · D8_l · tI32 · I4/mcm (140); type st:d8-l-cr5b3-ti32; tier A: standard phase name; confidence high
Stoichiometry: Pr 0.6250, Si 0.3750
Stability: stable in 1 of 1 calculated diagram(s): 300–1670.8 K, x(Si) 0.375–0.375
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:pr5si3-d8l
tdb: tdb:PrSi-20Xu.tdb:PR5SI3_D8L

TDB models of PR5SI3_D8L (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PR5SI3_D8L, type code %, sha256 5164e34ad4f5ccca…

50: PHASE PR5SI3_D8L % 2 5 3 !
51: CONST PR5SI3_D8L : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

PR5SI4 (Pr–Si)

Id: phase:pr-si:pr5si4; status assigned
Structure: Si4Zr5 · tP36 · P4_12_12 (92); type st:si4zr5-tp36; 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: Pr 0.5556, Si 0.4444
Stability: stable in 1 of 1 calculated diagram(s): 300–1795.19 K, x(Si) 0.44444–0.44444
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:pr-si:pr5si4
paper: paper:10.1111/jace.17031:Pr5Si4
tdb: tdb:PrSi-20Xu.tdb:PR5SI4

TDB models of PR5SI4 (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PR5SI4, type code %, sha256 5164e34ad4f5ccca…

55: PHASE PR5SI4 % 2 5 4 !
56: CONST PR5SI4 : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase; reports values for this phase

PR5SI9_ALPHA (Pr–Si)

Id: phase:pr-si:pr5si9-alpha; status assigned
Structure: Gd5Si4 · oP36 · Pnma (62); type st:gd5si4-op36; 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, polymorph_family:other phases of this system have the same composition); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Pr 0.3571, Si 0.6429
Stability: stable in 1 of 1 calculated diagram(s): 300–305.34 K, x(Si) 0.64286–0.64286
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:pr-si:pr5si9-alpha
tdb: tdb:PrSi-20Xu.tdb:PR5SI9_ALPHA

TDB models of PR5SI9_ALPHA (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PR5SI9_ALPHA, type code %, sha256 5164e34ad4f5ccca…

70: PHASE PR5SI9_ALPHA % 2 5 9 !
71: CONST PR5SI9_ALPHA : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase

PR5SI9_CC (Pr–Si)

Id: phase:pr-si:pr5si9-cc; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:stoichiometry_contradicts_C_c; stoichiometry_contradicts_C_c:PrSi-20Xu.tdb
Candidate (literature_printed): Si2Th · tI12 — printed with a label mapped to this phase
Candidate (name_token): Si2Th · C_c · tI12 · I4_1/amd (141) — Strukturbericht/word 'CC' in the TDB name
Candidate (sgte_mmc2): Si2Th · C_c · tI12 · I4_1/amd (141) — Hallstedt 2025 mmc2 row for PR5SI9_CC: Pr5Si9 (high T)
Candidate (tdb_comment): Si2Th · tI12 · I4_1/amd — PrSi-20Xu.tdb: 'Prototype Si2Th (tI12, I4_1/amd)'
Stoichiometry: Pr 0.3571, Si 0.6429
Stability: stable in 1 of 1 calculated diagram(s): 305.34–1972.55 K, x(Si) 0.64286–0.64286
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:pr-si:pr5si9-cc
paper: paper:10.1111/jace.17031:β-Pr5Si9
tdb: tdb:PrSi-20Xu.tdb:PR5SI9_CC

TDB models of PR5SI9_CC (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PR5SI9_CC, type code %, sha256 5164e34ad4f5ccca…

75: PHASE PR5SI9_CC % 2 5 9 !
76: CONST PR5SI9_CC : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase; reports values for this phase

PRSI_B27 (Pr–Si)

Id: phase:pr-si:prsi-b27; status assigned
Structure: FeB · B27 · oP8 · Pnma (62); type st:b27-feb-op8; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaaotk and oqmd-7935, space group 62
Stoichiometry: Pr 0.5000, Si 0.5000
Stability: stable in 1 of 1 calculated diagram(s): 300–1933.48 K, x(Si) 0.5–0.5
Literature: 3 values (3 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:pr-si:prsi-b27
mp: mp:mp-aaaaaotk
oqmd: oqmd:oqmd-7935
paper: paper:10.1111/jace.17031:PrSi
tdb: tdb:PrSi-20Xu.tdb:PRSI_B27

TDB models of PRSI_B27 (1): PHASE and CONSTITUENT statements as written

PrSi-20Xu.tdb: PRSI_B27, type code %, sha256 5164e34ad4f5ccca…

60: PHASE PRSI_B27 % 2 1 1 !
61: CONST PRSI_B27 : PR : SI : !

Example references (1 of 1; assessments first):

doi:10.1111/jace.17031 Kai Xu, Keke Chang, Xiaobing Zhou, Leilei Chen, Junwen Liu, Zixuan Deng et al., Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics, J Am Ceram Soc 103, 3812-3825 (2020).
assessment that models this phase; reports 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}
}