EFFECT OF DOPANTS ON THE MICROWAVE DIELECTRIC PROPERTIES OF 2xCeO 2 -xCaO-xTiO 2 (x=1/4) DIELECTRIC RESONATORS P. S. Anjana a , M. T. Sebastian * a , Anna-Karin Axelsson b and Neil McN. Alford b a Ceramic Technology Division, Regional Research Laboratory, Trivandrum 695 019, India b Physical Electronics and Materials, Faculty of Engineering, London South Bank University, 103 Borough Road, London SE1 OAA, U. K. Abstract 2xCeO 2 -xCaO-xTiO 2 (x=1/4)(CCaT) microwave dielectric ceramics has been prepared by conventional solid state ceramic route. The ceramics has been characterized using X-Ray Diffraction, SEM, EDAX and microwave methods. CCaT has relatively high dielectric constant (ε r ) of 65, quality factor Q u xf=9500 GHz and high temperature variation of resonant frequency (τ f =+399 ppm/ 0 C). The effect of addition of dopants of differing valencies on the microwave dielectric properties is studied. The dielectric constant is found to decrease with increase in the dopant concentration except for niobium pentoxide. The τ f decreases with increase in concentration for chromium oxide, manganese oxide and ferric oxide. Keywords: dielectric resonators, microwave dielectric materials 1. Introduction Wireless telecommunication is perhaps the sector of electronic industry showing the more dramatic growth in the past two decades. This is due to the improved performance of dielectric resonator (DR) at microwave frequencies. Reducing the size is very important for high quality and low cost devices. The important characteristics required for a dielectric resonator are high İ r for miniaturization, high Q u for selectivity and low temperature variation of the resonant frequency for stability. Although several materials have been reported 1-3 for practical applications, active research is still going on for new ceramics with improved properties that can satisfy all these requirements. But it is difficult to find materials that satisfy all the three required characteristics. The properties can be tailored by adding suitable additives. It is known that addition of certain dopants increase the density and improve the microwave dielectric properties of materials 4,5 . The objective of the present study is to develop new dielectric materials for practical applications by the addition of suitable dopants to the parent compound and thus tailor the microwave properties. 2.Experimental The DR samples were prepared by the conventional solid state ceramic route. CeO 2 (IRE), CaCO 3 (Aldrich), TiO 2 (Aldrich) were used as starting materials. They were weighed in stoichiometric proportions and ball milled for one day using zirconia balls in distilled water media. The slurry was dried and then calcined for 10 hours at 1150 0 C. The calcined powders were ball milled for 5 days in distilled water using zirconia balls. The fine powders were * Corresponding Author