Structural dielectric and electrical conducting properties of KB ' B '' O-6 (B ' = Nb, Ta; B '' = W, Mo) ceramics

The polycrystalline samples of the defect pyrochlore-type KB 'B "O-6(B ' = Nb, Ta; B " = W, Mo) compounds were prepared by solid-state reaction techni que. The formation of the compounds was checked by X-ray diffraction (XRD) technique. All the compounds have cubic crystal structure at room temperatu re. Detailed studies of dielectric parameters (epsilon, tan delta) in wide frequency (10(3)-10(6) Hz) and temperature (300-600 K) range reveal that th e compounds do not have any dielectric anomaly in the studied frequency and temperature range. Detailed studies of electrical properties (viz. ac and de conductivity, transference number) as functions of various parameters, e .g. frequency, biasing de electric field, temperature, etc., are carried ou t. (C) 2001 Elsevier Science Ltd. All rights reserved.