Diffuse phase transition in Ba 5YTi 3− xZr xNb 7O 30 ferroelectrics

Abstract

The polycrystalline samples of Ba 5YTi 3− x Zr x Nb 7O 30 ( x=0,1,2,3) complex tungsten–bronze-type compounds were prepared by a high-temperature solid-state reaction technique. Room temperature preliminary X-ray diffraction (XRD) studies suggest the formation of single-phase compounds with an orthorhombic structure. Detailed studies of dielectric constant ( ε) and tangent loss (tan δ) of the above compounds as a function of frequency (200 Hz–1 MHz) at room temperature, and also as a function of temperature (liquid nitrogen to 350 °C) at different frequencies (1, 10, 10, 100 kHz and 1 MHz) show that the above compounds have diffuse ferroelectric phase transition with relaxor properties. Transition temperature ( T c) of the materials decreases with increase in diffusivity ( γ) for higher concentration of Zr. Study of dc resistivity has been carried out from room temperature to 400 °C.