Functional Ceramics Of Batio <sub> 3 </ Sub> Preparation, Characterization And Ferroelectric, Dielectric Performance

Based on the sol-gel method, we used two different organic solvents to prepare BaTiOj powders. One way is stearic acid-gel method, using barium hydroxide and titanate butoxide as reactants, stearic acid as solvent; the other is lactic acid-gel method, using barium acetate and titanate butoxide as reactant, ethylene glycol monometheyl ether as solvent, adding lactic acid as chelating agent. The dry-gel was investigated by DTA-TG to determine the properly annealing temperature. The BaTiO, nanocrystal was gained by annealing dry-gel at different temperatures above 600癈 in the air. The BaTiO3 powder was characterized by three ways in detail. 1 .The chemical content was characterized by chemical analysis and X-ray fluorescence analysis. The ratio of Ba and Ti is about 1. 2.The crystalline BaTiO, was characterized by XRD. It showed the nanocrystalline BaTiO3 was tetragonal. The peaks were width because the particle was too small, which leaded to the split of the peaks was not obvious. The powder exhibited reliable purity. 3. The particle size and its distribution were determined by TEM, LKY-3 particle size analyzer and laser scatter particle size analyzer. From the TEM, the gain size was in the range of 20-100 nm. From the particle size analyzers, the size distribution was obtained, and it showed the distribution is narrow.The BaTiO3 ceramics was prepared by sinstering the powder. The polarization field hysteresis was measured at 50 Hz by using RT 6000 ferroelectric detecting system apparatus at room temperature. The dielectric properties, capacitance-frequency and dielectric loss-frequency characteristics were measured by using HP 4294 A impedance analyzer. The ceramics showed well-satureated polarization-field (P-E) hysteresis loops. The values of the spontaneous polarization, remaanant polarization and coercive field were found to be 5.512, 12.285 fjC-cm'2 and 3 342 V ?m~l , respectively. The valure of the dielectric constant was 2713. Moreover, we discuss the difference of the single-crystal and ceramics and the effect of the different voltages and particle size. From the dielectric-frequency figure, when the frequency is between 200-150 000 Hz, the ceramics has good stability dielectric constant and the dielectric loss tangent is small. So the ceramics can be used to make some electronic components.