Synthesis and properties of lead-free BNT-BT-xCZ ceramics as high-temperature dielectricsY

Bulk ceramic samples of the perovskite series (1-x)(0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3))-xCaZrO(3) with 0 <= x <= 0.2 were prepared using the conventional solid-state route. It is shown that careful characterization of Bi2O3 raw materials is essential to avoid deviations from the nominal composition. X-ray diffraction analysis reveals formation of perovskite main phase, and a relaxor-like response of the relative permittivity over temperature was observed. Flattening of the permittivity-temperature curves is observed with increasing CaZrO3 fraction, while maintaining low dielectric losses over a wide temperature range. Samples with x = 0.2 exhibit a temperature stable permittivity of epsilon(r) approximate to 600 (Delta epsilon(r)'/epsilon(r,mid)' approximate to 10 % between -80 degrees C and 300 degrees C) along with small dielectric losses (tan delta < 0.02 between -55 degrees C and 265 degrees C) at 1 kHz. These attributes qualify these compositions as suitable high temperature capacitor dielectric materials.