Investigation on microwave dielectric properties and microstructures of (1-x) LaAlO3-xCa0.2Sr0.8TiO3 ceramics

The structural, microstructural and microwave dielectric properties of (1 - x) LaAlO3-xCa(0.2)Sr(0.8)TiO(3) ceramics prepared by the conventional solid state ceramic route have been investigated. The formation of solid solutions (1 - x) LaAlO3-xCa0.2Sr0.8TiO3 was confirmed by the X-ray diffraction patterns and the EDS analysis. The lattice parameter, average grain size and dielectric constant (epsilon(r)) increase with increasing amount of Ca0.2Sr0.8TiO3 whereas the quality factor (Q x f) decreases. The increasing temperature coefficient of resonant frequency (tau(f)) caused by the decreasing tolerance factor with x ranging from 0.3 to 0.7. The tau(f) can be tuned near zero at x = 0.5. Specimen with the composition of 0.5LaAlO(3)-0.5Ca(0.2)Sr(0.8)TiO(3) possesses an excellent combination of microwave dielectric properties: epsilon(r) similar to 32.7, Q x f similar to 33400 GHz, tau(f) similar to -2.5 ppm/degrees C. (C) 2015 Elsevier B.V. All rights reserved.