Sintering behavior and microwave dielectric properties of (Ca, La)(Ti, Al)O-3 ceramics

Abstract

The dielectric and sintering properties of (1 - x)CaTiO3-xLaAlO(3) were investigated. The greater the amount of LaAlO3, which has a lower sintering temperature than CaTiO3, the higher the relative density is obtained. As x increased in (1 - x)CaTiO3-xLaAlO(3), the following phase transformation occurred: orthorhombic (x less than or equal to 0.4) --> pseudocubic (x = 0.5) --> rhombohedral(x greater than or equal to 0.6). The microwave dielectric properties of epsilon(r) = 37, Q . f(0) = 47,000 (at 7 GHz): and tau(f) = 5 ppm/degrees C were obtained at 0.65CaTiO(3)-0,35LaAlO(3). Also, various compounds of low melting point were added to 0.5CaTiO(3)-0.5LaAlO(3) in order to decrease the sintering temperature. When 3 wt% of 0.97Bi(2)O(3)-0.03Al(2)O(3) or 0.76Bi(2)O(3)-0.24NiO as sintering additive was added, the sintering temperature was lowered from 1600 degrees C to 1450 degrees C; and the relative dielectric constant (epsilon(r)) and the temperature coefficient of the resonant frequency (tau(f)) were not changed: whereas the Q . f(0) values were lowered by about 15% and 34%, respectively.