TY - JOUR
T1 - Synthesis, Characterization, and Polymorphism of [H3O][NbF6]: A Polar and Possibly Ferroelectric Oxonium Salt
AU - Möbs, Martin
AU - Sachs, Malte
AU - Rolheiser, Konstantin
AU - Pietzonka, Clemens
AU - Karttunen, Antti J.
AU - Kraus, Florian
N1 - Publisher Copyright:
© 2024 The Authors. European Journal of Inorganic Chemistry published by Wiley-VCH GmbH.
PY - 2024/5/22
Y1 - 2024/5/22
N2 - [H3O][NbF6] was obtained from the controlled hydrolysis of NbF5 in anhydrous liquid HF. It adopts a polar, orthorhombic crystal structure with space group Iba2 (no. 45, oI88) at room temperature. A first-order phase transition at 137 K leads to a cubic non-centrosymmetric polymorph in space group I213 (no. 199, cI88). This low-temperature modification results from a distinct rotation of the [H3O]+ cations canceling their polar orientation in the room temperature phase. Quantum-chemical calculations estimate a rotational barrier between 5.8 to 6.4 kJ/mol. At a temperature of 363 K, the compound adopts a centrosymmetric, cubic crystal structure in space group Pm (Formula presented.) m (no. 221, cP11) that shows rotational disorder of cations and anions. The transition from the polar phase at room temperature to the centrosymmetric phase at high temperature not only reveals the plastic nature of the high-temperature structure but also hints at potential ferroelectric properties, underscoring the multifaceted behavior of [H3O][NbF6] across different temperature regimes.
AB - [H3O][NbF6] was obtained from the controlled hydrolysis of NbF5 in anhydrous liquid HF. It adopts a polar, orthorhombic crystal structure with space group Iba2 (no. 45, oI88) at room temperature. A first-order phase transition at 137 K leads to a cubic non-centrosymmetric polymorph in space group I213 (no. 199, cI88). This low-temperature modification results from a distinct rotation of the [H3O]+ cations canceling their polar orientation in the room temperature phase. Quantum-chemical calculations estimate a rotational barrier between 5.8 to 6.4 kJ/mol. At a temperature of 363 K, the compound adopts a centrosymmetric, cubic crystal structure in space group Pm (Formula presented.) m (no. 221, cP11) that shows rotational disorder of cations and anions. The transition from the polar phase at room temperature to the centrosymmetric phase at high temperature not only reveals the plastic nature of the high-temperature structure but also hints at potential ferroelectric properties, underscoring the multifaceted behavior of [H3O][NbF6] across different temperature regimes.
KW - crystal structures
KW - fluoride
KW - niobium
KW - Oxonium
KW - polymorphism
KW - quantum-chemical calculations
UR - http://www.scopus.com/inward/record.url?scp=85189986178&partnerID=8YFLogxK
U2 - 10.1002/ejic.202400015
DO - 10.1002/ejic.202400015
M3 - Article
AN - SCOPUS:85189986178
SN - 1434-1948
VL - 27
JO - European Journal of Inorganic Chemistry
JF - European Journal of Inorganic Chemistry
IS - 15
M1 - e202400015
ER -