Synthesis of 0.65CaTiO(3)-0.35SmAlO(3) ceramics and effects of La2O3/SrO doping on their microwave dielectric properties

0.65CaTiO(3)-0.35SmAlO(3) ceramics were synthesized via four calcination methods using a conventional solid-state technique. The reaction mechanism occurred between mixtures of CaCO3, TiO2, Sm2O3, and Al2O3 was studied by X-ray diffraction patterns. Sm2TiO7, CaSmAl3O7, Sm4Ti9O24 were detected in calcined mixtures, which could be converted into CaTiO3-SmAlO3 in ultimate sintered ceramics at a high temperature. Through comparing the comprehensive properties of 0.65CT-0.35SA ceramics sintered at 1450 degrees C, we determined the best calcination path as the fourth method. We then introduced La2O3/SrO to CTSA ceramics synthesized by the fourth method to improve the overall properties. Thereafter, the phase composition, microstructure, densification, dielectric performances and sintering characteristic of 1wt% SrO doped 0.65CT-0.35SA specimens with various La2O3 additions were comprehensively investigated. We observed that after adding La2O3/SrO additives, the sintering temperature of CTSA ceramics was depressed to 1340 degrees C, while facilitating dielectric performances. However, the second-phase La10Al4O21 occurred due to the excessive amounts of La2O3 additions, which degraded the dielectric properties of 0.65CT-0.35SA ceramics. Synthetical properties of epsilon(r)=42.94, Qxf=43680GHz (f=5.1GHz), and (f)=-3.39ppm/degrees C were achieved for 1wt% SrO doped 0.65CT-0.35SA specimens with 0.5wt% La2O3 additions sintered at 1340 degrees C, which were likely to be promising option for practical application.