Structural, dielectric and electrical studies of Ba5SmTi3Nb7O30 ferroelectric ceramics

Ferroelectric materials have significant scientific and industrial applications. Out of different structural groups of ferroelectric materials, tungsten-bronze structured ferroelectric materials have attracted attention of researchers because of their interesting ferroelectric, pyroelectric, piezoelectric and nonlinear optical properties. In this work, specimen of composition Ba5SmTi3Nb7O30, a tungsten bronze structured material, was prepared and investigated. The preparation conditions for this compound have been optimized. X-ray diffraction (XRD) analysis reveals the formation of single-phase compound with orthorhombic structure. Scanning electron microscopy was used to investigate grain morphology of the material. The average grain size of the compound is found out to be in the range of 4 □m. Dielectric properties of the compound have been studied as a function of frequency and temperature. The variation of dielectric constant (□′r) with temperature at various frequencies show that the compound undergoes a diffuse type ferro - paraelectric phase transition. At different frequencies, the variation of dielectric loss (tan □) with temperature shows that the loss is almost constant initially but at higher temperatures it increases sharply. The frequency dependence of dielectric constant and loss show a decreasing trend upto 10 kHz and beyond this frequency it remains almost constant. The temperature dependence of ac and dc conductivity of the compound have been investigated. The activation energy has also been calculated from the Arrhenius plot.