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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Light Element Analysis Facility (LEAF): Light Element Analysis Facility (LEAF)
Irvine, J. T. S. (PI), Baker, R. (CoI) & Miller, D. N. (CoI)
EPSRC
5/04/20 → 4/04/23
Project: Standard
Electon Microscopy: Electon Microscopy for the characterisation and manipulation of advanced function materials and their interfaces at the nanoscale
Irvine, J. T. S. (PI), Baker, R. (CoI) & Zhou, W. (CoI)
EPSRC
1/04/18 → 2/09/20
Project: Standard

Structural polytypism in B-site deficient azetidinium-based pnictogen halide hexagonal perovskites (dataset)
Liu, H. (Creator), Rae, R. (Contributor), Dalzell, J. (Contributor), Fruchtl, H. (Contributor), McKay, A. (Contributor), Cordes, D. B. (Contributor), Kumar, A. (Contributor), Kirk, C. (Contributor) & Morrison, F. (Creator), University of St Andrews, 30 Jun 2025
DOI: 10.17630/c47693ff-3017-4dc9-a7d8-4385765b9d37
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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.

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

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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

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

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