Impedance Spectroscopy of ( Bi _1/2 Na _1/2 ) TiO ₃ – BaTiO ₃ Ceramics Modified with ( K _0.5 Na _0.5 ) NbO ₃

Abstract

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 .