Significant enhancement in quality factor of Zn(2)TiO(4) with Cu-substitution

Abstract

Zinc orthotitanate (Zn(1-x)Cu(x))(2)TiO(4), 0 <= x <= 0.20, spinel samples were prepared by solid state reaction and sintering. 1060 degrees C was the optimal sintering temperature for all the Cu-substituted samples which showed sintered density >= 94%, and maximum unloaded quality factor (Q(u)f). SEM microphotographs revealed fairly uniform grains between 2 and 20 mu m depending upon the composition. Microwave measurements at similar to 7.1-7.5 GHz on these samples (as dielectric resonators) showed with Cu-substitution a steep increase in Q(u)f value from 2100 GHz (for Zn(2)TiO(4), x = 0) to 15,200 GHz (for x = 0.10), a significant jump of over 7 times, while epsilon'(r) was similar to 20 (for x = 0) and similar to 18 (x = 0.10). The jump in Q(u)f in Cu-substituted samples was attributed partly to improved sintered density and partly to absence of paramagnetic Ti(3+), as revealed by electron spin resonance spectra at 9.1 GHz. (c) 2011 Elsevier B.V. All rights reserved.