Abstract
The origins of microwave dielectric properties (1−x)CaTiO3–x(Li0.5La0.5)TiO3 (0.2≤x≤0.8) ceramics, prepared by a conventional solid-state reaction method, were investigated based on the theory of bond valence. The XRD and SEM results showed that complete solid solutions with orthorhombic perovskite structure were formed in the whole investigated compositional range. The dielectric constant (ɛr), quality factor (Q×f) and temperature coefficient of resonant frequency (τf) were closely related to B-site, A-site and the difference between A-site and B-site bond valences of ABO3 perovskite compounds, respectively. As x value increased from 0.2 to 0.8, the dielectric constant increased from 198.3 to 276.8, the Q×f value decreased from 4340 to 1880GHz, and the τf value varied from +489.7 to −178ppm/°C. For practical applications, excellent microwave dielectric properties of ɛr=245, Q×f=2750GHz and τf=+0.75ppm/°C were obtained for 0.4CaTiO3–0.6(Li0.5La0.5)TiO3 ceramics.
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