Structure and dielectric properties of a new series of pyrochlores in the Ca-Sm-Ti-M-O (M = Nb and Ta) system

Abstract

The present work investigates the dielectric properties of pyrochlore type oxides, Ca-Sm-Ti-M-O (M = Nb and Ta) in the low frequency region (100 Hz-1 MHz) over the temperature range 30-100 A degrees C. The 1 MHz dielectric constants (K) of these oxides are in the range 23-108 and show low variation with frequency (1 kHz-1 MHz). The temperature coefficient of dielectric constant (TCK) over the temperature range varies from positive to negative values in the range 48 to -107 ppm/A degrees C. Rietveld analysis of the X-ray diffraction data establishes a cubic pyrochlore-type phase in the space group Fd3 m (no. 227).The grain morphology observation by scanning electron microscope shows well sintered grains.