Dielectric Properties of 0.9Ag_(0.9)Li_(0.1)NbO_3 - 0.1Bi_(0.5)K_(0.5)TiO_3 Ceramics

摘要

New ferrielectric 0.9Ag_(0.9)Li_(0.1)NbO_3 - 0.1Bi_(0.5)K_(0.5)TiO_3 ceramics have been obtained. At room temperature ceramics exhibit perovskite structure, which is close to rombohedral-tetragonal phase boundary. The dielectric properties of ceramics were investigated in wide frequency range from 20 Hz to 1 GHz at temperatures 200 K-750 K. 0.9Ag_(0.9)Li_(0.1)NbO_3 - 0.1Bi_(0.5)K_(0.5)TiO_3 ceramics exhibits a first order mixed order-disorder and displacive ferroelectric phase transition at T_C = 430 K. The phase transition dynamics is caused by relaxation soft mode at frequencies below 1 GHz and soft phonon mode at higher frequencies. In ferroelectric phase an additional dielectric dispersion is observed, which could be attributed to dipolar glass relaxation.