Chung-Long Pan

Structure and electrical properties of MgTiO3 thin films deposited by rf magnetron sputtering

Bulk MgTiO3 ceramics have shown excellent dielectric properties at microwave frequencies; however, the high sintering temperature of the bulk materials is major obstacle in their use as dielectric resonators to miniaturize microwave circuits. In this article, MgTiO3 thin films were fabricated on n-type Si(100) substrates by rf magnetron sputtering by using MgTiO3 target which was synthesized in the experiment. It was possible to obtain highly oriented MgTiO3(110) thin film at a rf power density of 7.7W∕cm2 and a substrate temperature of 400°C, which is much lower than the bulk sintering temperature. These films were studied by choosing different rf power densities and substrate temperature. The microstructure and surface morphology of the MgTiO3 films deposited on Si(100) was determined by x-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. The XRD showed that the deposited films exhibited a polycrystalline microstructure. The grain size of the film increased with an increa...

Microwave Dielectric Properties and Microstructures of CuO-Modified (1-x)(Mg0.95Co0.05)TiO3?xCaTiO3 Ceramic System

The effects of CuO additives on the microstructures and the microwave dielectric properties of (1-x)(Mg0.95Co0.05)TiO3–xCaTiO3 ceramics were investigated. The CuO additives can effectively reduce the sintering temperature of the ceramics to as low as 1175°C. With x = 0.08, at 1275°C, the 0.92(Mg0.95Co0.05)TiO3–0.08CaTiO3 ceramic possesses excellent microwave dielectric properties: a dielectric constant er of 22.1, a Q×f value of 86400 GHz (at 7 GHz) and a τf value of 5.4 ppm/°C. Sintered ceramic samples were characterized by using X-ray diffraction pattern and SEM. Dielectric constants (er) are not significantly affected by various additives and range from 20 to 23. By properly adjusting the x of (1-x)(Mg0.95Co0.05)TiO3–xCaTiO3 ceramics, small temperature coefficients (< ±3 ppm/°C) of resonant frequency (τf) are obtained for 0.93(Mg0.95Co0.05)TiO3–0.07CaTiO3 with 0.25 wt% CuO additives.