Influence of CaF2 on the structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 ceramics

Abstract

Ag(Nb0.8Ta0.2)O3 ceramics were prepared by the traditional solid-state reaction method. The effect of CaF2 addition on the structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 ceramics was investigated. The addition of CaF2 led the ceramics to a larger grain size and distortion of lattice. With the addition of 4.5 wt.% CaF2, the permittivity of the ceramics increased from 442 to 1028, the dielectric loss decreased sharply from 6.12 × 10−3 to 8.6 × 10−4, and the temperature coefficient of capacitance decreased from 1834 ppm/°C to −50 ppm/°C (at 1 MHz). These results indicated that the high permittivity was related with a large grain size, a low grain boundary density, and the weak Ta-O or Nb-O bond strength caused by the addition of CaF2.