A room-temperature nitrite-based hybrid bimetal molecular ferroelectric material: [(R)-3-quinuclidinol]2[LiCo(NO2)6]

Abstract

Organic–inorganic hybrid molecular ferroelectrics have attracted broad attention in the field of research of ferroelectric materials. Following the surge of stable candidates, hybrid bimetal molecular-based materials have been recently explored to achieve excellent ferroelectricity. However, rare hybrid bimetal molecular ferroelectrics were reported. Inspired by “ferroelectrochemistry”, a chiral nitrite-based hybrid bimetal molecular ferroelectric material, [(R)-3-quinuclidinol]₂[LiCo(NO₂)₆] (1), was reported. The ferroelectric-paraelectric phase transition (C2 ↔ P321) behaviour of 1; was found at 343 K (Curie temperature, T_c) with a spontaneous electronic polarization (P_s) of 0.52 μC cm⁻² and a coercive field (E_c) of 48 kV cm⁻¹ at 298 K. Various-temperature single crystal structural analysis and dielectric constant measurements reveal that the rapid rotation of the organic cation and slight order–disorder transition of the NO₂⁻ anion are the origin of the ferroelectricity. To our knowledge, 1 is the first example of a nitrite-based hybrid bimetal molecular ferroelectric material that is triggered by an external electric field. This finding establishes a clear stimulus–structure–response relationship in advanced hybrid ferroelectric materials.