Multi-step phase transition crystal with dielectric constant bistability and temperature-dependent conductivity.

Here, we report the crystal structures, phase transitions, and thermal, dielectric, and conducting properties of an ion-pair compound [C-bmim][Ni(mnt)] (1). 1 undergoes a three-step phase transition with four phases before melting. A two-step dielectric constant bistability is also realized by the structural phase transition in 1 occurring among phases I, II, and III, which is due to the in-plane oscillations of the alkyl chain and crystal-to-mesophase transition, respectively.