Phase transitions in Pb(Yb1/2Nb1/2)O-3-PbTiO3 solid solutions

Abstract

High-resolution heat capacity measurements of (1 - x)Pb(Yb1/2Nb1/2)O3-xPbTiO3 with x = 0, 0.02, 0.04, 0.06, 0.08 were carried out in the temperature range from 80 K to 590 K using a modified adiabatic calorimeter. The dielectric constant was also obtained for x = 0 and 0.02 samples between 300 K and 600 K at the measuring frequency of 10 kHz. The beat capacity data clearly reveal that the transition is of the first-order nature. The transition temperature decreases linearly and the heat capacity peak associated with the transition becomes broader as x increases. An anomaly in dielectric constant was also observed at the transition temperatures. It is of particular interest to note that the transition revealed by both heat capacity and dielectric constant is most abrupt at x = 0.02, not x = 0, and the origin of this peculiar behavior seems to lie in the dynamics.