Microwave dielectric properties of Zn(Nb1-xTax)2O6 ceramics

Microwave dielectric ceramics Zn(Nb1-xTax)(2)O-6 were prepared by conventional mixed oxide route. The crystal structure and microwave dielectric properties of Zn(Nb1-xTax)(2)O-6 ceramics were investigated systematically using X-ray powder diffraction (XRPD) and a network analyzer. Two kinds of solid solutions based on the ZnNb2O6 and ZnTa2O6 structure, respectively, were observed in this binary system. The sintering temperature of ceramics increased from 1150 to 1350 degreesC as x value ranged from 0 to 1.0. The dielectric properties exhibited a significant dependence on the sintering condition, composition and crystal structure of the ceramics. The dielectric constant (er) of Zn(Nb1-xTax)(2)O-6 ceramics increased with increasing Ta content, and ranged from 23.05 at x=0 to 35.8 at x=1. In contrast, the quality factors (Qxf) of this system decreased with increasing Ta content, the highest Qxf values of sintered ceramics changed linearly, and ranged from 82,200 to 56,417 GHz as x values increased from 0 to 1.0. The temperature coefficient of resonant frequency (tau(f)) changed from -71.16 ppm/degreesC at x = 0 to +8.94 ppm/degreesC at x = 1, and a zero temperature coefficient of resonant frequency (tau(f)) for Zn(Nb1-xTax)(2)O-6 ceramics system was obtained at x = 0.65. (C) 2003 Elsevier B.V. All rights reserved.