Electric field-induced phase transition from the glasslike to paraelectric phase and dielectric spectra hardening in PMN single crystal

Abstract

One of the key points in the physics of the relaxors is their response to the applied DC field. Many studies of this topic were made, in particular on the influence of the field on the dielectric properties. However, practically, in all the cases, the measurements were performed at a fixed frequency and usually with the change in the temperature at the fixed field strength. In this paper, we report the evolution of the dielectric spectra at low frequencies (0.1 Hz [Formula: see text] 1 kHz) at fixed temperature 246 K on changing the DC electric field applied in (111) from 1 kV to 7 kV. Cole-Cole function was used to describe the spectra and the field dependences of the mean relaxation time [Formula: see text], the oscillation strength [Formula: see text] and the width parameter [Formula: see text] were determined. The obtained [Formula: see text]([Formula: see text]) and [Formula: see text] [Formula: see text]([Formula: see text]) provide evidence of the field-induced transition from the nonpolar glass-like phase to the nonpolar paraelectric phase at around 1.5 kV/cm. In the paraelectric phase, very fast hardening of the spectra was observed with [Formula: see text] changing from 10 s to about [Formula: see text]s. The performed analysis demonstrated that the earlier reported positive C-V effect is completely determined by the spectra hardening, while [Formula: see text][Formula: see text] does not show any change in the glass-like phase and monotonously decreases with a field increase in the paraelectric state. For complete understanding of the microscopic origin of the observed phenomena, a detailed study on the short-and long-range structures at the same condition is necessary.