Double Hysteresis Loops And Temperature-Field Phase Diagram In Pb(Mg1/3nb2/3)O-3-29.5%Pbtio3

Polarization-electric field (p-E) hysteresis loops in 70.5%Pb(Mg1/3Nb2/3)O-3-29.5%PbTiO3 (PMN-29.5%PT) have been observed in the temperature range between 40 degrees C and 200 degrees C. In temperature range above the phase transition temperature under zero biasing field, the ferroelectric critical endpoint (CEP) in the temperature-field phase diagram in the dc biasing field applied along the [001](c) direction (in the cubic coordinate) has been found at 138.5 degrees C and 1.2 kV cm(-1), while the temperature dependence of the spontaneous polarization has been clarified in the ferroelectric phase. Our experimental results of the ferroelectric CEP and spontaneous polarization in PMN-29.5%PT have been discussed on the basis of the Landau-type phenomenological theory.