Dielectric properties of (Na0.5Bi0.5)TiO3-Ba0.7Sr0.3Sn0.02Ti0.98O3 composite ceramics

摘要

Lead-free x(Na0.5Bi0.5)TiO3-(1 - x)Ba0.7Sr0.3Sn0.02Ti0.98O3 (NBT-BSST) ceramics are prepared by a wet solid-phase reaction method. The effect of NBT/BSST ratio on phase structure, microstructure and dielectric properties has been investigated in detail. The X-ray diffraction (XRD) analysis illustrates that the composites are composed of tetragonal perovskite. With increasing NBT content, the ceramic capacitors display stronger temperature stability in its dielectric behavior. A great enhance of dielectric properties and other electric parameters is obtained in this system by properly modulating the compositions. For example, the composite ceramics with 30% NBT content possess a large dielectric constant (epsilon(r)) of 3200 and a low dielectric loss (tan delta) of 0.09. The temperature coefficient of capacitance of NBT-BSST varies from -50% to 20% while the NBT content is 30% at the whole range of measured temperature. The results show that NBT-BSST ceramics are a good candidate of lead-free dielectric materials.