The influence of axial pressure on relaxor properties of BaBi2Nb2O9 ceramics

On the basis of our studies it results that dielectric properties of BaBi2Nb2O9 ceramics are sensitive to axial pressure applied. The pressure causes an increase of dispersion in the real part of dielectric permittivity ɛ′(T,f) and a rise in the temperature Tm at which the maximum in ɛ′(T,f) dependence occurs. The applied pressure induces in the ɛ′(T) dependence an additional step-like anomaly, which appears at the temperature TA < Tm. The applied pressure shifts both Tm and TA at the same rate, i.e. dTA/dX = dTm/dX = +14 °C/kbar at high axial pressure range, above the threshold pressure Xthresh. The Vogel–Fulcher relationship is employed to determine the axial pressure influence on relaxor properties of BBN ceramics. The simulated order parameter q takes non-zero values below Burn‘s temperature TB, where the polar clusters appear on cooling. For pressures higher than 0.8 kbar, the TB changes at the rate dTB/dX = −200 °C/kbar. The decrease in the difference between Burnʹs TB and the freezing Tf temperatures induced by the applied axial pressure is observed. This could be ascribed to the narrowing of temperature range of relaxor behavior.