Structural phase transition and dielectric switching in an organic-inorganic hybrid rare-earth double perovskite-type compound:(DMP)_(2)LaRb(NO_(3))_(6)(DMP=N,N-dimethylpyrrolidinium cation)

In recent years,it has been found that the flexibility of structure and diversity of the components endow quite an amount of the organic-inorganic hybrid perovskites with novel properties,i.e.,structural phase transitions.Considering the natural advantage of the perovskite-type structure in generation of stimuliresponsive or smart materials,we synthesized an organic-inorganic hybrid rare-earth double perovskitetype compound,(DMP)_(2) LaRb(NO_(3))_(6)(DMP=N,N-dimethylpyrrolidinium cation,1).It shows reversible phase transition at 219/209 K(heating/cooling).Variable-temperature single-crystal structure analysis and dielectric constant measurements reveal that the thermal vibrations of the polar cation guests and the distortion of the anionic cage-like framework are the origin of the phase transition.Meanwhile,the movement of polar cation in crystal lattices arouses dielectric transition between the low-and highdielectric states,resulting in a switchable property of dielectric constant.The results reveal that the rare-earth double perovskite provides a promising platform for achieving switchable physical/chemical properties.