Ce0.75Y0.25O1.875: New temperature-stable microwave dielectric ceramics with high Q values for microwave application

Ce0.75Y0.25O1.875, new microwave dielectric ceramics which presented high quality factors and stable resonant frequency temperature coefficient, were prepared successfully via the method of solid-state reaction. The sintering behavior, crystal structure and microwave dielectric properties of the new ceramics had been investigated afterwards. The Ce0.75Y0.25O1.875 ceramics presented a single phase indexed as CeO2 structure which belonged to Fm-3m (225) space group, cubic system. The grain size of the Ce0.75Y0.25O1.875 ceramics was calculated to evaluate the grain growth. The dielectric constant (epsilon(r)) of the Ce0.75Y0.25O1.875 ceramics, which could reflect the microwave dielectric properties, was on the dependence of relative densities. The Q x f values, which could be explained by packing fraction and grain size, had been further investigated. The resonant frequency temperature coefficient (tau(f)) of the Ce0.75Y0.25O1.875 ceramics was related to the dielectric constant. The excellent microwave dielectric properties of the new Ce0.75Y0.25O1.875 ceramics was epsilon(r) = 19.75, Q x f = 96600 GHz, tau(f) = -22.53 ppm/degrees C.