Diffuse phase transition in Ba5YTi3−xZrxNb7O30 ferroelectrics

The polycrystalline samples of Ba5YTi3−xZrxNb7O30 (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 (Tc) 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.