Dehydration-triggered structural phase transition-associated ferroelectricity in a hybrid perovskite-type crystal

Since the appearance of Rochelle salt, ferroelectrics have received extensive attention from researchers due to they are playing an important role in sensors, memories, mechanical actuation, and so on. In recent years, with the rapid development of molecular ferroelectrics, high-performance molecular ferroelectrics have become effective complement to inorganic ferroelectrics. However, compared with inorganic ferroelectrics, the family of molecular ferroelectrics is relatively scarce, and exploring high-performance ferroelectric materials through new synthesis strategies has become the trend of molecular ferroelectrics. Here, we successfully transformed non-polar material 1 (2-H2PCA)2(H2O)CdCl6 (2-H2PCA = 2-picolylamine cation) into polar material 2 (2-H2PCA)2CdCl6 by single-crystal to single-crystal transformation (SCSCT). Meanwhile, 2 exhibits clear ferroelectricity with a high-temperature Tc of 378 K, a Ps of 1.18 μC cm−2 at 300 K. This work not only realizes the purpose of synthesizing ferroelectrics by forming polar structures by SCSCT, but also realizes the reversibility of SCSCT, which provides ideas for the construction and exploration of new molecular ferroelectrics.