The Rare-Earths influences on doped BaTiO3-Ceramics Microstructure and Electric Characteristics

Abstract

The influence of rare-earth additive content on microstructure and electric properties of doped BaTiO3 ceramics is investigated. The concentration of Er2O3 and Yb2O3 in the doped samples range from 0.01 to 1.0at % . The samples are prepared by the conventional solid state reaction, and sintered at 1320° and 1350°C in air atmosphere for 4 hours. SEM analysis shows that all samples are characterized by polygonal grains. The uniform and homogeneous microstructure with grain size ranged from 20 to 45μm is the main low doped samples characteristics. For the samples doped with the higher dopant concentration (0.5 and 1.0 at%) the average grains size is ranged from 5 to 10μm. Dielectric measurements are carried out as a function of temperature up to 180°C at different frequencies. The low doped samples display the high value of dielectric permittivity at room temperature. A nearly flat permittivity-temperature response is obtained in specimens with higher additive content. The Curie temperature of doped samples were ranged from 126 to 130°C. The Curie constant for all series of samples decrease with increment of dopant concentration and the lowest values is mesured from samples doped with 0.01 wt% of aditive. The obtained value of γ pointed out that the specimens have almost sharp phase transition. Also, the specific electrical resistance is measured in function of temperature at the different frequencies from 100Hz to 1MHz. With increasing additives concentration, the electrical resistance decreases to the concentration of 0.5 at% and then increases.