Compositionally graded multilayer Ba_xSr_(0.95-x)Ca_(0.05)TiO_3 ceramics prepared by tape casting for use as dielectric materials

摘要

Compositionally graded multilayer Ba_xSr_(0.95-x) Ca_(0.05)TiO_3 (BSCT) ceramics were prepared via tape casting method using nanometer powders from co-precipitation. Microstructures and dielectric properties of the BSCT system were investigated. The powders were characterized by using transmission electron microscope and BET surface area measurement. Surface morphologies of the sintered samples and multilayer structure were examined by scanning electron microscopy. BSCT particles were of spherical shape with diameters in the range of 73-93 nm. Their specific surface areas were in the range of 11.7-14.6 m~2/g. The graded BSCT ceramics with nine layers laminated in vertical way exhibited a higher sintered density, with an average grain size of 0.4 um, after sintered at 1,200 ℃. Dielectric constant, dielectric loss and tunability of the graded ceramics were 2223.94,1.5 x 10~(-3)at2 MHz and 42.9% at 3.0 kV/mm, with good dielectric temperature and frequency stability, which made it a promising candidate used for tunable ceramic capacitors and phase shifters.