Some aspects of dimensionality and phase transitions of organic–inorganic hybrid perovskite (n-C14H29NH3)2ZnCl4

Abstract

The differential scanning calorimetery and the differential thermal analysis thermograms were performed over a suitable wide range of temperatures on polycrystalline samples of the titled hybrid. Furthermore, the ac conductivity σ ac(ῳ,T) and the complex dielectric permittivity e *(ῳ,T) as function of temperature 120 K < T < 400 K and some selected frequencies in the range 1 kHz ≤ f ≤ 100 kHz were measured and presented. The combination of the measured parameters confirms, without any doubt, the existence of a first-order reversible solid–solid structural phase transition from intercalation to non-intercalation, at T ≈ 368 K accompanied by a sudden increase of the interlayer spacing by ≈17.5%. The analysis of our data is based on the coordination complex and the dimensionality of the central metal halide arrangements, which, in our case, is isolated square [ZnCl4]−2 tetrahedral coordination and, hence, of zero-dimensionality (0D), but stabilized in a two-dimensional structure through charge-assisted hydrogen-bonding system. The zero-dimensionality results in a large charge density and, hence, of high efficiently packed compared with other hybrids of this series which are usually crystallized in two-dimensional (2D) corner-sharing [MCl6]−2. The rule of hydrogen bonding has been considered. The odd–even effects were given.