Search

Molecular ferroelectrics of high‐temperature reversible phase transitions are very rare and have attracted increasing attention in recent years. In this paper is described the successful synthesis of a novel high‐temperature host‐guest inclusion ferroelectric: [(C6H5NF3)(18‐crown‐6)][BF4] (1) that shows a pair of reversible peaks at 348 K (heating) and 331 K (cooling) with a heat hysteresis about 17 K by differential scanning calorimetry measurements, thus indicating that 1 undergoes a reversible structural phase transition. Variable‐temperature PXRD and temperature‐dependent dielectric measurements further prove the phase‐transition behavior of 1. The second harmonic response demonstrates that 1 belongs to a non‐centrosymmetric space group at room temperature and is a good nonlinear optical material. In its semiconducting properties, 1 shows a wide optical band gap of about 4.43 eV that comes chiefly from the C, H and O atoms of the crystals. In particular, the ferroelectric measurements of 1 exhibit a typical polarization‐electric hysteresis loop with a large spontaneous polarization (Ps) of about 4.06 μC/cm2. This finding offers an alternative pathway for designing new ferroelectric‐dielectric and nonlinear optical materials and related physical properties in organic‐inorganic and other hybrid crystals. [ABSTRACT FROM AUTHOR]