Microwave dielectric properties of CeO2-0.5AO-0.5TiO2 (A = Ca, Mg, Zn, Mn, Co, Ni, W) ceramics

Microwave dielectric ceramic materials based on cerium [CeO2-0.5AO-0.5TiO(2) (A= Mg, Zn, Ca, Mn, Co, Ni, W)] have been prepared by a conventional solid state ceramic route. The crystal structure was studied by X-ray diffraction, microstructure by scanning electron microscopy (SEM) techniques and the phase composition was studied using energy dispersive X-ray analysis (EDXA). The sintered ceramics had a relative dielectric constant (epsilon(r)) in the range 17-65 and quality factor Q(u)xf up to 50,000 GHz and a temperature variation of resonant frequency (tau(f)) ranging from a negative value (-62 ppm/degrees C) to a high positive value (+399 ppm/degrees C). The majority of the synthesized ceramics were of a two phase composite consisting of a fluorite CeO2 and perovskite ATiO(3) phase. The microwave dielectric properties were further tailored by adding various amounts of dopants of different valencies to the calcined powder. This made it possible to either tune tau(f) to zero or improved the quality factor further. (c) 2007 Elsevier Ltd. All rights reserved.