A novel low-loss (1-x)(Ca0.8Sr0.2)TiO3-xSmAlO3 microwave dielectric ceramics with near-zero temperature coefficient

Abstract

(1-x)Ca0.8Sr0.2TiO3-xSmAlO3 (abbreviated as (1-x)CST-xSA) perovskite ceramics were synthesized through the conventional solid-state reaction process. The effects of SmAlO3 on the microstructure, low-frequency dielectric performances, and microwave dielectric properties for (1-x)CST-xSA ceramics were investigated systematically. All compositions exhibited an orthorhombic perovskite structure with dense surface morphology. With increasing the content of SmAlO3, the order of B-site cation revealed a trend of increase first and then slowly decreased. The presence of oxygen vacancies in the (1-x)CST-xSA ceramics was detected by using x-ray photoelectron spectroscopy. Excellent temperature stability of dielectric permittivity and low dielectric loss (tanδ lower than 0.005) were observed for (1-x)CST-xSA ceramics at low frequencies. For x = 0.35 composition, the temperature coefficient of the resonant frequency approached zero. In addition, the dielectric permittivity of 42.0, the quality factor of 39,120 GHz, and the temperature coefficient of resonant frequency of − 6.4 ppm/℃ were obtained for 0.65CST-0.35SA ceramics. It is suggested that (1-x)CST-xSA ceramics can be used as a candidate material for various microwave communication components.