Broadband dielectric spectroscopy of Ba(Zr,Ti)O₃ and related solid solutions

Broadband dielectric spectra (from Hz up to THz and infrared frequencies) of the xBaZrO₃ - (1-x)BaTiO₃ (BZT) ceramic solid solutions will be presented. We studied the BZT system in a broad concentration and temperature ranges from 10 to 700 K.
BZT is a model lead-free system which, depending on the concentration x, behaves as incipient, relaxor, diffuse or classical ferroelectric material. The behaviour is compared to that of pure BaTiO₃ and BaZrO₃ end members. Based on the results of the broadband fits of the spectra, we will discuss different processes and their origins that play role in the dynamics, such as (soft) phonons and relaxations. The spectra are characterized by an overdamped central mode in the microwave range which weakens on cooling. Except for BaTiO₃, the soft mode and central mode do not soften appreciably and do not contribute substantially to the low-frequency permittivity maximum. The most important dielectric contribution is brought by Cole-Cole relaxation assigned to the hopping of Ti ions in the BaTiO₃ clusters, which obeys the Arrhenius law.
In the same manner we will also present the BZT system doped with niobium.