Ferroelasticity and piezoelectricity of organic–inorganic hybrid materials with a one-dimensional anionic structure: so similar, yet so different

The synthesis, structural aspects, thermal and dielectric analysis for new members of the ferroic family, polynuclear Bi(III) and Sb(III) halide complexes based on a pyrazolium cation with the formulas (C3N2H5)[BiCl4]center dot H2O and (C3N2H5)[SbCl4]center dot H2O, are presented. The former compound was found to undergo a ferroic phase transition of the ferroelastic type at 213/219 K (cooling/heating scans), whereas, the latter one exhibited a piezoelectric feature in the dielectric response function. The molecular motions of pyrazolium cations were analyzed based on the spin-lattice relaxation time of H-1 NMR measurements.