Structural, dielectric and electrical properties of Sr5RTi3Nb7O30.(R = Gd and Dy) ceramics

Polycrystalline samples of Sr5RTi3Nb7O30 (R=Gd and Dy) were prepared by a high-temperature, solid-state reaction technique. The formation of single-phase compounds in the orthorhombic crystal system was confirmed by an X-ray diffraction (XRD) technique. Microstructural analysis by scanning electron microscopy (SEM) suggests that the compounds have small grains distributed uniformly on the surface of the sample. Detailed studies of dielectric properties suggest that the compounds undergo ferroelectric-paraelectric diffuse phase transition well above the room temperature. Measurement of conductivity/ resistivity as a function of temperature suggests that the compounds have semiconducting properties above 373 K with negative temperature coefficient. (C) 2003 Elsevier Science B.V. All rights reserved.