Tailoring the microwave dielectric properties of Sr0.6Ca0.4LaAlO4 ceramic by TiO2 addition

Sr0.6Ca0.4LaAlO4 ceramic was fabricated via solid-state sintering route and the effect of TiO2 addition on its microwave dielectric properties was investigated. Sr0.6Ca0.4LaAlO4 formed as the major phase along with LaAlO3 as a minor phase at 1400 degrees C. However, the concentration of LaAlO3 phase increased with increase in the sintering temperature and it became a major phase at 1475 degrees C. Maximum density was obtained for the composition with x = 0 (i.e., Sr0.6Ca0.4LaAlO4 ceramics) sintered at 1450 degrees C for 4 h. The TiO2 addition lowered the maximum densification temperature to 1400 degrees C from 1450 degrees C. The microwave dielectric properties varied linearly with increasing the volume fraction of TiO2 (x value). Relative permittivity (epsilon(r)) increased from 20.7 to 31.1, Q(u)f(o) decreased from 95,250 to 65,000 GHz, and tau(f) was tuned through zero and increased from - 29.5 to + 25.4 ppm/degrees C with increase in the x value from 0 to 0.2. In the present study, epsilon(r) approximate to 24.8, Q(u)f(o) approximate to 83,500 GHz, and a near-zero tau(f) approximate to - 2.5 ppm/degrees C was obtained for the composition with 10wt% addition of TiO2.