Dielectric Properties of Chromium Doped Ba[sub 5]Ti[sub 2]O[sub 7]Cl[sub 4

Abstract

For the environment protection, lead free materials are needed such as KNbO3, BaTiO3, Ba5Ti2O7Cl4 etc. This paper includes the growth of Ba5Ti2O7Cl4 ferroelectric single crystal. The single crystals of Ba5Ti2O7Cl4 grown by fused method by taking a mixture of BaCO3, TiO2 and BaCl2 in the molar ratio of 1.5:1:1 with an impurity of chromium oxide (CrO3 = 0.005gm). It is orthorhombic at room temperature. The properties of the crystals are strongly affected by the technique of crystal growth as well as by adding external impurities i.e. dopants. In this paper we present the effect of doping on the dielectric studies of Ba5Ti2O7Cl4 single crystals. The dielectric constant and dc conductivity were determined simultaneously from room temperature to Curie temperature. The simultaneous measurement of capacitance (C) and resistance (R) were carried out to determine dielectric constant and conductivity respectively. The slight changes were occurred at room temperature from sample to sample. But at the Curie temperature of about 920 °C, the value of dielectric constant is in the range of 108 to 109. The conductivity at this temperature was found to be equal to 1.85(ohm‐cm)−1. The dc conductivity changes with increasing temperature up to 920 °C and then rises to a high value at the Curie temperature of about 920 °C. The temperature at which the dielectric constant and conductivity is high called Curie temperature. The Curie temperature of this crystal is about 920 °C