Dielectric properties of Ba5MTi3A7O 30 [M = Ce, Pr, Nd, Sm, Gd, Dy and Bi; A = Nb, Ta] ceramics

Abstract

Polycrystalline Ba5MTi3A7O30 [M = Ce, Pr, Nd, Sm, Gd, Dy and Bi; A = Nb, Ta] ceramics were prepared as single-phase materials through conventional solid-state ceramic route. The structure was studied by X-ray diffraction method and dielectric properties were measured in the frequency range 100 Hz-1 MHz from room temperature to 250°C. At 1 MHz their dielectric constant (εr) varies from 164 to 887 and loss tangent (tan δ) from 10-3 to 10 -2. The study indicates a ferroelectric-paraelectric diffuse phase transition in Ba5MTi3Nb7O30 [M = Ce, Pr, Nd, Sm, Gd, Dy and Bi] ceramics above room temperature. But Ba 5MTi3Ta7O30 [M = Ce, Pr. Nd, Sm, Gd, Dy and Bi] ceramics show linear variation of εr at and above room temperature. The measured dielectric properties indicate that these materials are possible candidates for the fabrication of discrete multilayer capacitors in microelectronic technology. © 2004 Elsevier B.V. All rights reserved.