Influence of Zr-substitution on phase transitions character in polycrystalline Ba(Ti1−x Zr x )O3

The results of X-ray diffraction, scanning electron microscopy, and dielectric measurements performed for polycrystalline Ba(Ti1−x Zr x )O3 are presented. Data from these measurements show a change of the type of paraelectric–ferroelectric (PE–FE) phase transition (PT) from sharp PT (x < 0.10), through diffuse phase transition (0.10 ≤ x ≤ 0.20), to relaxor type one (x = 0.30). The lack of structural PT at the temperature T m (the temperature of the maximum of real part of the electric permittivity ε′) for 0.10 ≤ x ≤ 0.30, suggest that this PE–FE transition is not connected with the change of crystal structure. A phase angle of about Φ ≈ −90°, between electric current and applied voltage, suggests the occurrence of polar regions (clusters) below 400 K. The change of these clusters polarizability and their lability at the T m is postulated as possible origin of the observed maximum of ε′.