Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites

Hang Liu; Rebecca Rae; James Dalzell; Gavin S. Peters; Herbert  Früchtl; Aidan P. McKay; David B. Cordes; Amit Kumar; Caroline A. Kirk; Finlay D. Morrison

doi:10.1021/acs.inorgchem.5c01374

Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites

Hang Liu^*, Rebecca Rae, James Dalzell, Gavin S. Peters, Herbert Früchtl, Aidan P. McKay, David B. Cordes, Amit Kumar, Caroline A. Kirk, Finlay D. Morrison^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Azetidinium (Az⁺)-based antimony and bismuth organic–inorganic hybrid halide B-site-deficient perovskite analogues Az₃B₂X₉ (B³⁺ = Sb, Bi; X^– = Cl, Br, I) were systematically studied. All Az₃B₂X₉ stoichiometries adopt hexagonal close-packed perovskite structures with the 6H (hcc)₂ stacking sequence, differing only in the positions of the ordered B-site vacancies. In Az₃Sb₂Cl₉ and Az₃Sb₂Br₉ ordering of B-site vacancies in a single face-sharing octahedral layer leads to the formation of an unusual 2D layered polar structure with the P6₃mc space group. Variable-temperature single-crystal and powder XRD, DSC, DTA, and dielectric spectroscopy showed several successive phase transitions at low temperatures associated with distortions of the octahedral framework and order/disorder of the Az⁺ cation. In contrast, in Az₃Sb₂I₉, Az₃Bi₂Br₉, and Az₃Bi₂I₉, the preferred arrangement of vacancies at corner-sharing octahedral sites generates a 0D “dimer” structure. This work highlights the flexibility for structural variations based on particular configurations of vacancy ordering in B-site-deficient halide perovskites.

Original language	English
Number of pages	15
Journal	Inorganic Chemistry
Volume	ASAP
Early online date	26 Jun 2025
DOIs	https://doi.org/10.1021/acs.inorgchem.5c01374
Publication status	E-pub ahead of print - 26 Jun 2025

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@article{d448b45d0d364b2fbad9dd304915d28e,

title = "Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites",

abstract = "Azetidinium (Az+)-based antimony and bismuth organic–inorganic hybrid halide B-site-deficient perovskite analogues Az3B2X9 (B3+ = Sb, Bi; X– = Cl, Br, I) were systematically studied. All Az3B2X9 stoichiometries adopt hexagonal close-packed perovskite structures with the 6H (hcc)2 stacking sequence, differing only in the positions of the ordered B-site vacancies. In Az3Sb2Cl9 and Az3Sb2Br9 ordering of B-site vacancies in a single face-sharing octahedral layer leads to the formation of an unusual 2D layered polar structure with the P63mc space group. Variable-temperature single-crystal and powder XRD, DSC, DTA, and dielectric spectroscopy showed several successive phase transitions at low temperatures associated with distortions of the octahedral framework and order/disorder of the Az+ cation. In contrast, in Az3Sb2I9, Az3Bi2Br9, and Az3Bi2I9, the preferred arrangement of vacancies at corner-sharing octahedral sites generates a 0D “dimer” structure. This work highlights the flexibility for structural variations based on particular configurations of vacancy ordering in B-site-deficient halide perovskites.",

author = "Hang Liu and Rebecca Rae and James Dalzell and Peters, \{Gavin S.\} and Herbert Fr{\"u}chtl and McKay, \{Aidan P.\} and Cordes, \{David B.\} and Amit Kumar and Kirk, \{Caroline A.\} and Morrison, \{Finlay D.\}",

note = "Funding: H.L. would like to thank the University of St. Andrews for financial support via a St. Leonard{\textquoteright}s scholarship. The authors acknowledge facilities access made possible through support from the EPSRC Light Element Analysis Facility Grant EP/T019298/1 and the EPSRC Strategic Equipment Resource Grant EP/R023751/1.",

year = "2025",

month = jun,

day = "26",

doi = "10.1021/acs.inorgchem.5c01374",

language = "English",

volume = "ASAP",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society (ACS)",

}

TY - JOUR

T1 - Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites

AU - Liu, Hang

AU - Rae, Rebecca

AU - Dalzell, James

AU - Peters, Gavin S.

AU - Früchtl, Herbert

AU - McKay, Aidan P.

AU - Cordes, David B.

AU - Kumar, Amit

AU - Kirk, Caroline A.

AU - Morrison, Finlay D.

N1 - Funding: H.L. would like to thank the University of St. Andrews for financial support via a St. Leonard’s scholarship. The authors acknowledge facilities access made possible through support from the EPSRC Light Element Analysis Facility Grant EP/T019298/1 and the EPSRC Strategic Equipment Resource Grant EP/R023751/1.

PY - 2025/6/26

Y1 - 2025/6/26

N2 - Azetidinium (Az+)-based antimony and bismuth organic–inorganic hybrid halide B-site-deficient perovskite analogues Az3B2X9 (B3+ = Sb, Bi; X– = Cl, Br, I) were systematically studied. All Az3B2X9 stoichiometries adopt hexagonal close-packed perovskite structures with the 6H (hcc)2 stacking sequence, differing only in the positions of the ordered B-site vacancies. In Az3Sb2Cl9 and Az3Sb2Br9 ordering of B-site vacancies in a single face-sharing octahedral layer leads to the formation of an unusual 2D layered polar structure with the P63mc space group. Variable-temperature single-crystal and powder XRD, DSC, DTA, and dielectric spectroscopy showed several successive phase transitions at low temperatures associated with distortions of the octahedral framework and order/disorder of the Az+ cation. In contrast, in Az3Sb2I9, Az3Bi2Br9, and Az3Bi2I9, the preferred arrangement of vacancies at corner-sharing octahedral sites generates a 0D “dimer” structure. This work highlights the flexibility for structural variations based on particular configurations of vacancy ordering in B-site-deficient halide perovskites.

AB - Azetidinium (Az+)-based antimony and bismuth organic–inorganic hybrid halide B-site-deficient perovskite analogues Az3B2X9 (B3+ = Sb, Bi; X– = Cl, Br, I) were systematically studied. All Az3B2X9 stoichiometries adopt hexagonal close-packed perovskite structures with the 6H (hcc)2 stacking sequence, differing only in the positions of the ordered B-site vacancies. In Az3Sb2Cl9 and Az3Sb2Br9 ordering of B-site vacancies in a single face-sharing octahedral layer leads to the formation of an unusual 2D layered polar structure with the P63mc space group. Variable-temperature single-crystal and powder XRD, DSC, DTA, and dielectric spectroscopy showed several successive phase transitions at low temperatures associated with distortions of the octahedral framework and order/disorder of the Az+ cation. In contrast, in Az3Sb2I9, Az3Bi2Br9, and Az3Bi2I9, the preferred arrangement of vacancies at corner-sharing octahedral sites generates a 0D “dimer” structure. This work highlights the flexibility for structural variations based on particular configurations of vacancy ordering in B-site-deficient halide perovskites.

UR - https://www.scopus.com/pages/publications/105009327651

U2 - 10.1021/acs.inorgchem.5c01374

DO - 10.1021/acs.inorgchem.5c01374

M3 - Article

SN - 0020-1669

VL - ASAP

JO - Inorganic Chemistry

JF - Inorganic Chemistry

ER -

Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites

Abstract

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Light Element Analysis Facility (LEAF): Light Element Analysis Facility (LEAF)

Electon Microscopy: Electon Microscopy for the characterisation and manipulation of advanced function materials and their interfaces at the nanoscale

Vacancy Ordering and Polytypism in B-site Deficient Halide Perovskites (thesis data)