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New Family of Dielectric Materials in Ca–Y–Ti–Nb–O System Having Pyrochlore Type Structure
Author(s) -
Nair K. Ravindran,
Rao P. Prabhakar,
Raj Anupama V.,
Joseph Smila K.,
Chandran Marottikunnathu Raman,
Koshy Peter
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.01933.x
Subject(s) - pyrochlore , dielectric , stoichiometry , materials science , rietveld refinement , analytical chemistry (journal) , solid solution , phase (matter) , mineralogy , crystal structure , crystallography , chemistry , metallurgy , organic chemistry , optoelectronics
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 30°–100°C. Their temperature coefficient of the dielectric constant is negative and in the range −80 to −612 ppm/°C. 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.