| Abstract [eng] |
In this dissertation broadband dielectric spectroscopy results for different perovskites systems from simple inorganic to complex organic will be presented. In the first part of this study the effect of core – shell structure to dielectric properties is shown. In such system a thin layer of a shell compound (KNbO3, BaTiO3) surrounds and stresses the lattice of a core compound (BaTiO3, BiFeO3) which results in improved overall properties. Further an investigation of organics perovskites CH3NH3PbX3 (X = I, Br, Cl) and (CH3)2NH2Zn (HCOO)3 was performed. Experimental data revealed the nature of the dipolar relaxations and structural phase transitions, also it was concluded that both systems are non-ferroelectric compounds. Finally, the effect of mixing CH3NH3 and (CH3)2NH2 cations in CH3NH3Br3 system was studied. The high concentration of (CH3)2NH2 cation results in the significant broadening of dielectric anomaly and the suppression of tetragonal phase, due to frustrated state. In this work ferroelectric data, temperature dependences of dielectric permittivity in the broad frequency range (10-2 - 1011 Hz) and temperature dependences of acoustic attenuation and speed can be found. |
