New Family of Dielectric Materials in Ca–Y–Ti–Nb–O System Having Pyrochlore Type Structure

Abstract

A new family of pyrochlore-type oxides in the Ca-Y-Ti-Nb-O system has been prepared by the conventional solid-state route. These compounds have a dielectric constant (K) in the range 27-92 and, further, the dielectric properties are found to be independent of frequency in the 100 Hz to 1 MHz range for all the compositions in the temperature range 301-1001C. Their temperature coefficient of the dielectric constant is negative and in the range À80 to À612 ppm/1C. Rietveld analysis of the X-ray diffraction data establishes a cubic pyrochlore-type phase in the space group Fd3m (no. 227). A variation in the stoichiometry of the cations in the system does not change the pyrochlore-type structure. R. Ubic-contributing editorThe authors acknowledge the partial financial support from the International Centre for Diffraction Data (ICDD), Newton Square, Pennsylvania 19073-3273, for the grant (05-03).

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

“…Recently, the authors have reported a new family of dielectric materials in Ca-Y-Ti-Nb-O system for their dielectric properties. 14,15 The continuing drive to discover new materials with better dielectric properties suggests that the evaluation of new dielectric materials should be a fruitful area of research. In the present study, a series of pyrochlore type oxides with the chemical formula, PbRETiTaO 7 (RE5Y, La, Nd, Sm, Gd, or Dy) have been prepared which show somewhat low variation of dielectric properties in the temperature range 30-100uC.…”

Pyrochlore-based oxides with small temperature coefficient of dielectric constant

“…Recently, we reported pyrochlore based dielectric materials in Ca-Y-Ti-Nb-O system having dielectric constant ͑K͒ in the range of 27-92. 15 During the present study, we could prepare some solid solutions of niobates and tantalates in Ca-RE-Ti-M -O ͑RE=Sm or Dy and M =Nb or Ta͒ system, which also have pyrochlore-type structure and some of these solid solutions show only very small variation in dielectric constant when the temperature is varied from −50 to 100°C. The structure and dielectric properties of these materials and their variation with composition and temperature were investigated some what in detail and the results are presented in this paper.…”