Glassy freezing dynamics was investigated in ${\mathrm{BaZr}}_{0.5}{\mathrm{Ti}}_{0.5}{\mathrm{O}}_3$ (BZT50) ceramic samples by means of dielectric spectroscopy in the frequency range 0.001 Hz–1 MHz at temperatures $10<T<300$ K. From measurements of the quasistatic dielectric polarization in bias electric fields up to $\sim 28$ kV/cm it has been found that a ferroelectric state cannot be induced, in contrast to the case of typical relaxors. This suggests that—at least for the above field amplitudes—BZT50 effectively behaves as a dipolar glass, which can be characterized by a negative value of the static third order nonlinear permittivity. The relaxation spectrum has been analyzed by means of the frequency-temperature plot, which shows that the longest relaxation time obeys the Vogel-Fulcher relation $\tau ={\tau }_0\exp [E_0/(T-T_0)]$ with the freezing temperature of 48.1 K, whereas the corresponding value for the shortest relaxation time is $\sim 0$ K, implying an Arrhenius type behavior. By applying a standard expression for the static linear permittivity of dipolar glasses and/or relaxors the value of the Edwards-Anderson order parameter $q\left(T\right)$ has been evaluated. It is further shown that $q\left(T\right)$ can be described by the spherical random bond-random field model of relaxors.

• Received 1 April 2016

DOI:https://doi.org/10.1103/PhysRevB.93.224105