Impedance Spectroscopy of (Bi_(1/2)Na_(1/2))TiO_3-BaTi_O3 Ceramics Modified with (K_(0.5)Na_(0.5))NbO_3

摘要

The electrical and dielectric properties of (1 - x)(0.94Bi_(1/2) Na_(1/2)TiO_3-0.06BaTiO_3)-x(K_(0.5)Na_(0.5)NbO_3) with x = 0, 0.03, 0.09, 0.18 have been investigated by impedance spectroscopy over a wide temperature range. The dc conductivity of the ceramics follows the Arrhenius law with an activation energy ranging from ～1.20 to 1.50 eV. Measurements under different atmospheres show the materials exhibit n-type semiconducting behavior at elevated temperatures. The presence of a highly polarizable phase for all compositions is revealed by electric modulus (M") spectra. The Burns temperature decreases with increasing KNN content. The change in temperature-dependent permittivity with composition is explained by the difference in thermal evolution of polar nanoregions induced by the addition of KNN.