Microwave dielectric properties of (1− x)Ca<subscript>0.6</subscript>La<subscript>0.267</subscript>TiO<subscript>3</subscript> − xCa(Sm<subscript>0.5</subscript>Nb<subscript>0.5</subscript>)O<subscript>3</subscript> ceramics

Abstract: Microstructures and microwave dielectric properties of (1− x)Ca0.6La0.267TiO3 − xCa(Sm0.5Nb0.5)O3 (0.1≤ x ≤0.7) ceramics have been investigated. A two-phase system was formed in the given compositional range. The grain morphology exhibited two different types of grain: large circular grain and small square grain. With the increasing x value, the grain morphology of the small square grain became irregular. The microwave dielectric properties were strongly related to the composition. As the x value increased from 0.1 to 0.7, the dielectric constant (ɛ r) decreased from 87 to 48.3, the quality factor (Q × f) value from 14390 to 8360GHz, and the temperature coefficient of resonant frequency (τ f) value from +130.6 to −24.8ppm/°C, respectively. For practical application, an ɛ r of 74.3, a Q × f value of 12690GHz and a τ f value of +8.8ppm/°C were obtained for 0.7Ca0.6La0.267TiO3−0.3Ca(Sm0.5Nb0.5)O3 ceramics sintered at 1450°C for 4h. [Copyright &y& Elsevier]