The Research On Preparation,Structure And Properties Of Barium Titanate Based Nanotubes Thin Films

Ferroelectric thin film materials are widely used in today's society. It has good electrical and optical properties. It is widely used in the preparation of modern microelectronic devices, such as infrared sensors, capacitors and ferroelectric liquid crystals. The miniaturization of modern components is just the process of the ferroelectric thin film, the study of ferroelectric thin films has become the focus of the study of ferroelectrics. Since Barium titanate has been found to be ferroelectric, it has been playing a crucial role in the field of ferroelectric research, and now the study is gradually shifting from bulk ferroelectric to thin film ferroelectrics. Hydrothermal method has attracted more attention by experts and scholars for its simple operation, simple reaction conditions and no pollution. It is a novel research method to prepare barium titanate nanotubes thin films by hydrothermal method. Although it is still in the initial stage of exploration, research value has been showed.In this experiment, TiO2 nanotubes arrays (TiNTs) are the template. Pure barium titanate, rare barium titanate with Ce and barium strontium titanate nanotubes thin films are formed by adjusting the hydrothermal parameters, doping element. The research also studies microstructure, the phase composition, the dielectric properties and ferroelectric properties of the samples. By this, the research further studies the influence of hydrothermal parameters, rare earth elements doping, barium strontium ratio and annealing temperature on the formation of barium titanate and barium strontium titanate nanotubes thin films. The main results are as followed:(1)The study of hydrothermal parameters: Barium titanate nanotubes thin films are manufactured in 200?,0.1 M Ba(OH)2 and 2 hour hydrothermal, thus aren't effectively prepared at low temperature and low concentration are not effective. The prepared samples are cubic phase with highly ordered nano tubes structure, 12 ?m in the average thickness,and the volume effect. After annealing, the phase transformation becomes pseudo-cubic phase and tetragonal phase with smaller surface pore size and larger grain size. The dielectric constant is 634 and the dielectric loss is about 0.15. Both the microstructure and the dielectric properties are improved after annealing.(2)The study of Ce doping amount: The increasing doping amount, the grain size becomes smaller, the lattice constant "a" and the lattice distortion become larger, and the dielectric constant increases and then decreases. After annealing,the polycrystalline tetragonal nano tubes are obtained, with 100 nm diameter, 25 nm thickness, and 180 degree ferroelectric domain. At the same time, the maximum dielectric constant is 809, the dielectric loss is about 0.05, the remanent polarization Pr is 0.52 ?C/cm2 and the coercive field Ec is about 16.92 kV/cm.(3)The study of different barium strontium ratio: With the decrease of the ratio of Ba/Sr, both the crystal size and the dielectric constant become smaller, while the lattice constant "a" becomes larger. The hydrothermal synthesis of the BST20 sample directly generates a single crystal tetragonal phase structure,the others cubic one. The tetragonal phase nanotubes structure are obtained after annealing, with 12 ?m thickness in maximum,particle bulges and ferroelectric domain in 180 degree. Meanwhile, the maximum dielectric constant is 392, the dielectric loss is about 0.01, the remanent polarization Pr is 0.39 ?C/cm2 and the coercive field E. is 0.75 kV/cm.(4)The dielectric properties of barium titanate nanotubes thin films can be perfected by doping and annealing temperature.