Low temperature coefficient dielectric materials,PbRETiTaO 7 (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°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°C) as well as frequency (1 kHz to 1 MHz). The temperature coefficient of dielectric constant (TCK) over the temperature range 30–100°C is negative and varies in the range, −72 to −342 ppm °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×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.