High-Temperature Dielectric Relaxation in Pb(Mg_(1/3)Nb_(2/3))O_3-PbTiO_3 Single Crystals

摘要

We reported the dielectric properties of Pb(Mg_(1/3Nb_(2/3))O_3-PbTiO_3 single crystal in the temperature range of 300-1073 K and the frequency range of 100 Hz-10 MHz. Our results showed the coexistence of both true- and pseudo-relaxor behaviors in the crystal. The true relaxor behavior related to the paraelectric-ferroelectric phase transition occurs at～423 K. The pseudo-relaxor behavior appearing at～773 K was found to be related to oxygen vacancies. Further investigation reveals that the pseudo-relaxor behavior has fine structure: it contains two oxygen-vacancy-related relaxation processes. The low-temperature relaxation process is a dipolar relaxation created by the hopping motions of the oxygen vacancies, and the high-temperature relaxation process is a Maxwell-Wagner relaxation caused by the sample/electrode contacts.