Effects of Interfacial Polarization on Voltage Tunability of Pb(Fe1/2Nb1/2)1–xTixO3 Single Crystals

The voltage tunability of Pb(Fe1/2Nb1/2)1–xTixO3 single crystals is investigated at a low electric field (< 130 V/cm) in a low frequency range (< 1 MHz). The results show that the capacitance is strongly suppressed by the applied dc biases for both the rhombohedral sample and the tetragonal sample. A negative voltage tunability is only detected in the tetragonal sample. The origin of the giant tunability and the negative tunability is discussed based on the multipolarization-mechanism model and the equivalent circuit model, respectively. It is ascribed to the interfacial polarization at the interface of electrode/sample