Crystal structure and microwave dielectric properties of the low dielectric loss ZnZr1-xSnxNb2O8 ceramics

ZnZr1-xSnxNb2O8 (x=0.10, 0.15, 0.20, and 0.25) ceramics with improved microwave dielectric properties were prepared by conventional mixed oxide route. The effects of Sn4+ ion substitution on the microwave dielectric properties based on structural characteristics in this system were investigated systematically. Rietveld refinement was used to analyze the structure change of the sintered samples. Microscopic analysis showed that all the samples maintained the ZnZrNb2O8 phase with monoclinic structure. With the increase of Sn4+ content, the dielectric constant decreased attributed to the decrease of ionic polarizability. The Qxf value was dependent on, and increased monotonically with packing fraction. The temperature coefficient of resonant frequency (tau(f)) correlated with the variation of bond valence of B-site. The excellent microwave dielectric properties of epsilon(r)=27.37, Qxf=76,814 GHz (where f=7 GHz), and tau(f)= -55.09 ppm/degrees C were obtained for ZnZr1-xSnxNb2O8 (x=0.20) ceramics sintered at 1275 degrees C for 6 h. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.