Dielectric Properties of Ca1-xSm2x/3TiO3–Li1/2Ln1/2TiO3 Ceramics

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Abstract
The physical and microwave dielectric properties of Ca1- x Sm2 x /3TiO3–Li1/2Ln1/2TiO3 (Ln=Sm, Nd) have been investigated as a function of the degree of Sm substitution (x = 0.0 –1.0). As the calcium vacancy concentration increased with increasing Sm substitution, high Q ·f values were obtained due to the formation of a superlattice. The Q ·f values of the specimens with Nd increased throughout the entire composition range, due to the formation of complete solid solutions, while those of the specimens with Sm increased up to the solid solution limit x = 0.6, and then decreased due to the formation of a secondary phase Sm2Ti2O7. Dielectric constant (K) and temperature coefficient of resonant frequency (T C F) decreased linearly with increasing Sm substitution. In the (1- y)Ca2/5Sm2/5TiO3– yLi1/2Sm1/2TiO3 system, the microwave dielectric properties could be controlled by the variation of y. Typical values of K = 95.5, Q ·f = 7200 and T C F = 0 ppm/°C were obtained for 0.67Ca2/5Sm2/5TiO3–0.33Li1/2Sm1/2TiO3.