Microwave dielectric properties of (1−x)CeO2–xCaTiO3 and (1−x)CeO2–xSm2O3 ceramics

CeO2–CaTiO3 and CeO2–Sm2O3 microwave dielectric ceramics have been prepared by a conventional solid state ceramic route. The dielectric ceramics are characterized by X-ray diffraction, SEM, Raman and microwave methods. Ceria has a relative dielectric constant, εr, of 23, high dielectric quality factor×frequency product, Q×f up to 60,000 GHz with high temperature coefficient of resonant frequency, τf, of −53 ppm/°C. The addition of CaTiO3 and samarium oxide leads to a zero temperature variation of resonant frequency. The relative dielectric constant increases and Q decrease with CaTiO3 addition and the τr changes from a negative to a positive value. Sm2O3 addition of up to 50 mol% increases Q, decreases εr and improves the τf. The microwave dielectric properties are measured at low temperatures down to 20 K. The effect of addition of 1 mol% of various rare earth oxides on the microwave dielectric properties of ceria has also been investigated.