Analysis of high temperature phase transitions of copper doped (C2H5NH3)2CdCl4 perovskite

The synthesis of ethyl-ammonium-cadmium-chloride (C2H5NH3)2CdCl4 (EA-CdCl4) and copper doped EA-CdCl4 (EA-CdCuCl4) is interested. Infra-red and Raman temperature-dependant spectra are reported. The calorimetric study of (EA-CdCl4) and (EA-CdCuCl4) revealed three phase transitions at 219 K, 358 K, 383 K and two phase transitions at 333 K, 358 K respectively. In order to characterize these transitions, Raman spectra have been recorded in the wide temperature range (300 ≤ T ≤ 450 K) and the frequency range related to the internal and external vibrations of the cations and anions (4000-50 cm−1). Raman study confirms the presence of the structural phase transitions already observed by calorimetric DSC measurements for both (EA-CdCl4) and (EA-CdCuCl4) perovskites. The phase transitions manifest by anomalies in temperature dependence of wave number and full width at half maximum (FWHM) of several vibrational modes. The comparative study revealed the Cu-doping effect on structural parameters and phase transitions.