Effect of frequency and temperature on dielectric relaxation of [1 1 1]-oriented PMN-32PT single crystals

• The dielectric relaxor behavior of PMN-32PT single crystals was investigated.
• The diffuseness degree was enhanced with the increasing frequency at T > Tm.
• The diffuseness degree was varied with the increasing temperature at T > Tm.
• Dipole steering hysteresis explains the relation between dispersity and frequency.
• The RNRs explains the relation between diffusion degree and temperature.

The temperature dependence of dielectric permittivity of [1 1 1]-oriented PMN-32PT single crystals was measured at different frequencies. The modified Curie–Weiss and Lorentz-type laws were used to describe the dielectric relaxor behavior of PMN-32PT single crystals. It was indicated that the diffuseness degree was dependent on the measuring frequency and temperature. The diffuseness degree was enhanced with the increase of the measuring frequency. It was believed that the dipole steering hysteresis was responsible for the improvement of the diffuseness degree with the increase of measuring frequency. Furthermore, the diffuseness degree was also varied with the increase of the temperature above Curie temperature. The main reason for the change of diffuseness degree with the measuring temperature was attributed to the development of polarization of nanosize regions with the measuring temperature.