Synthesis And Characterization Of Barium Titanate And Cobalt Ferrite Powders For Preparation Of Magneto Electric Composites PDF Download

Barium titanate was synthesized using a solid state approach and an aqueous method. Solid state syntheses were used to prepare barium titanate pellets using a powder metallurgy method. Appropriate amounts of barium carbonate and titanium dioxide powder were mixed together in an agate mortar. Barium titanate pellets were mixed according to 5 different ratios of Ba/Ti which are 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1. Pellets were sintered in air at a temperature 1400 °C. Barium titanate thin films were prepared using an aqueous method. Sol-gel of barium titanate was prepared according to the similar ratios as pellets. Thin films of barium titanate sol-gel were deposited using a desktop printer onto a glass substrate and fired at 400 °C. Both pellets and thin films were characterized by X-ray diffraction, scanning electron microscope, Atomic Force Microscope (thin films only), and impedance spectroscopy. This thesis focuses on determination of dielectric properties of barium titanate including the resistance, capacitance, dielectric constant, relaxation frequency, and loss tangent. The highest density for the barium titanate pellets were 5.90 g/cm3 when a Ba:Ti ratio of 1:1 was used. The average thicknesses of the thin films were 2.89 nm as measured using the atomic force microscope and verified using the scanning electron microscope. Characteristic of barium titanate were observed under various temperatures starting from room temperature up to 450 °C (for pellets) and 300 °C (for thin films). The measured dielectric constant of the pellets at 10 kHz (at room temperature) varied from a maximum of 2810 to a minimum of 1375.