Dielectric studies of phase transitions in (Pb1−xBax)ZrO3

Abstract

Phase transitions in semiwet derived (Pb1−xBax)ZrO3 ceramics for the composition range 0⩽x⩽0.30 have been investigated by dielectric measurements at various frequencies during heating and cooling cycles. The paraelectric (PE) to ferroelectric (FE) to antiferroelectric (AFE) sequence of phase transitions is observed for 0⩽x<0.20. On increasing the Ba2+ content from x=0 to x=0.05, the thermal hysteresis associated with the AFE–FE phase transition increases from 11 to 100 °C. This is attributed to the increase in the piezoelectric coupling between the strain and polarization. For x=0.20, the FE phase does not transform into the AFE phase on cooling. Pronounced deviations from the regular FE behavior are observed on increasing the Ba2+ content to x=0.25. For x=0.30, the temperatures corresponding to the peak values of the real and imaginary parts of the dielectric constant become frequency dependent indicating relaxor FE behavior. It is shown that the polar clusters present in the PE phase undergo Vogel–Fulcher type relaxational freezing in the relaxor FE phase. The results of temperature dependent polarization measurements confirm the findings of the dielectric studies. It is proposed that Ba2+ substitution modifies the AFE and FE interactions of the PbZrO3 matrix in such a manner that their strengths become comparable for x=0.30 leading to the glassy or relaxor behavior.

Investigation of phase transition in ferroelectric Pb0.70Sr0.30TiO3 thin films

“…For a sharp transition, ␥ϭ1 and for a diffuse transition it lies in the range 1Ͻ␥р2. 23 We obtained the parameter ␥ϭ1.47 by fitting the experimental data ͑the fitting curve is shown in the inset of Fig. 2͒.…”

Electrical conduction mechanism and phase transition studies using dielectric properties and Raman spectroscopy in ferroelectric Pb0.76Ca0.24TiO3 thin films

“…8 Pokharel and Pandey reported values of ␥ in the range of 1.25-1.50 for the diffuse behavior of the (Pb 1Ϫx Ba x )ZrO 3 system. 32 In addition, Ganesh and Goo reported values of ␥ in the range of 1.20-1.34 for the diffuse behavior of the paraelectric-ferroelectric transition region for the (Pb 1Ϫx Ca x )TiO 3 system. 7 In order to study the current transport mechanism in our system, the current-voltage characteristics were obtained at different diode temperatures and the results are plotted in Fig.…”

“…For a sharp transition, ␥ϭ1 and for a diffuse transition it lies in the range 1Ͻ␥р2. 32 We obtained the parameter ␥ϭ1.33 by fitting the experimental data ͑the fitting curve is shown in the inset of Fig. 3͒.…”

Dielectric Properties of Nanostructured PZTSynthesised by Chemical Methods

“…This will produce a peak in dielectric constant ( ') versus temperature plot. By increasing the measuring frequency, the relaxation of smaller clusters occurs at lower temperatures because of their smaller relaxational time, producing shift in the peak 17 . This slow relaxational dynamics may be due to the correlated motion of Pb 2+ ions about their displaced sites.…”

“…4. Peaks in the dielectric constant plots are attributed to the phase transition from the ferroelectric tetragonal to the antiferroelectric rhombohedral structure 17 . In ferroelectrics, there will be more than one orientational state for the dipoles in the absence of electric field and these switchover from one state to other under the external electric field.…”