Microwave dielectric properties in the (1−x)(Na1/2La1/2)TiO3−x(Li1/2Sm1/2)TiO3 ceramic system

Microwave dielectric properties have been investigated in the ceramic system (1−x)(Na1/2La1/2)TiO3−x(Li1/2Sm1/2)TiO3. In this system, (Na1/2La1/2)TiO3 (NLT) exhibits relative permittivity (εr) of 122, dielectric Q value (Q) of 3260 and a positive temperature coefficient of resonant frequency (τr) of 480 ppm/°C at 3 GHz. On the other hand, (Li1/2Sm1/2)TiO3 (LST) shows εr=52, Q=760 and τf=−260 ppm/°C at 3 GHz. Therefore, an appropriate mixing of these two components yields material with both high permittivity and temperature-stable resonant frequency. From X-ray diffraction analyses, it was found that the ceramics are single phase perovskites. We have found that ceramics at the composition x=0.7 in this system (sintered at 1300 °C) have high εr of 117, Qf products of 2281 and temperature coefficient of resonant frequency τf=−l9 ppm/°C at 3 GHz.