Investigation On Spectra Of Barium Titanate Ceramics Materials

Barium titanate ceramics materials, which have the structure of oxygen octahedron , are the representative ferroelectric crystal. They, which possess excellent piezoelectric and dielectric properties, occupy very important position in detection, conversion, disposal and memory of information , and so on. Specially, the speciality of PTCR of doped barium titanate semiconductor ceramics have wide applications in thermister and basic control components. The objective of this thesis is to seek after the change rule of microstructure and the influence on ferroelectric properties in BaTiO3 by element doping ,and to establish the relation of ions doping and the tetragonal structure change of BaTiO3 as well as the influence on properties.In this work, a typical ferroelectric material, BaTiO3 is selected because it possesses a simple perovskite structure. Barium titanate ceramics materials, doped alkali and alkaline earth are prepared by sol-gel method. The doping bring on different kinds of point defects, and then the order degree of atoms in equilibrium positions changed. We have investigated the effect of substitution on A and B sites on the structure and properties by the analysis of XRD, IR and UV-Vis spectra. The mechanisms among them have been also tentatively discussed.We discussed the influence on doping and Ti-O octahedrons aberration as well as curie temperature, aging effect by spectra test and the measure of ferroelectric properties and time stability. It was found that the IR and UV-Vis spectra both have corresponding disciplinary change along with the change of doping concentration and the ions radial. The polarization effect and oxidation ability of doping ions both produce an effect on the position of absorption edges in UV-Vis spectra.In addition, the influence of element doping and substitution on aging effect of Barium titanate ceramics materials has been investigated. The results indicate that the concentration of point defects is one of the important factors which affect the stability performance of materials, and the FTIR is a potential way to characterize the stability of this kind of materials. We have found that the location of the oxygen vacancies in crystal structure of BaTiO3 might have an important effect on stability. Moreover, the studies show that the aberration of Ti-O octahedrons may induce the change of the absorption wavenumber of Ti-O bond, and may be the reason why curie temperature , remanent polarization and the coervive field changed.