Low temperature coefficient dielectric materials, PbRETiTaO7 (RE=Y, La, Nd, Sm, Gd, or Dy) having pyrochlore type structure

Abstract

The present work investigates the dielectric properties of pyrochlore type oxides, PbRETiTaO7 (RE=Y, La, Nd, Sm, Gd, or Dy) in the low frequency region (100 kHZ-1 MHz) at temperatures between 30 and 100 degrees C and the microwave frequency region. The 1 MHz dielectric constants (K) are in the range 43-99 and show somewhat low variation with temperature (30-100 degrees C) as well as frequency (1 kHz to 1 MHz). The temperature coefficient of dielectric constant (TCK) over the temperature range 30-100 degrees C is negative and varies in the range, -72 to -342 ppm degrees C-1. The dielectric constant in the microwave frequency region is in the range 23-43. Among the samples, PbGdTiTaO7 shows very good quality factor (Q x f) of 4008 in the microwave frequency region. They all have cubic pyrochlore type structure as indicated by powder X-ray diffraction patterns. The sintered microstructure shows well formed grains without much porosity.