Synthesis And Properties Of Single And Double Element Doped Barium Titanate Obtained By Hydrothermal (or Solvothermal) Method

At present, BaTiO₃is one of the most dynamic and the most widely used advancedceramic materials. Since1940the discovery of BaTiO₃, it has played an important role inmodern ceramic industry. In recent years, the development direction has developed alongmore performance oriented and miniaturization. The dielectric of high dielectric constant,low loss and high-temperature stabilizing shows more attention and expectation andmore research in the field has been developed. Under thus background, this paper beginswith developing performance of BaTiO₃ceramic material doped with different elements.In order to improve dielectric-frequency stability and dielectric-temperature stability, thephysicochemical properties and related mechanisms have been investigated.1. For the preparation of BaTiO₃ceramics with optimum properties, it is necessary toobtain highly active and high purity powder first. The method for the synthesis of dopedBaTiO₃is the variety of ways, it is an effective and economic way with inexpensivecompound of barium and titanate to prepare BaTiO₃. In this paper, the influence onsynthesizing BaTiO₃powders with different titanate precursors has been investigated, theoptimum synthesis conditions was carried out. Experiments indicate that highly pure,monodisperse, narrow diameter distribution, nanometric and size controllable BaTiO₃powder synthesized with hydrothermal method at lower temperature.2. Nd-doped barium titanates were successfully synthesized via a hydrothermal route.The influence of Nd³⁺content on dielectric properties was studied. The results indicatethat Nd doped barium titanate shows high dielectric constant and low dielectric loss, thestability of dielectric properties-frequency and dielectric properties-temperature has a dramatic increase. With the improvement of Nd content, the dielectric constant and thedielectric loss decrease rapidly. The impure phase BaTi₂O₅appeared after high heatsintering with the further improvement of Nd content. Results analysisof lattice parameters of Nd-doped barium titanates reveales that the substituent position ofNd is A site in BaTiO₃.3. Considering the high dielectric constant and low phase transition temperature ofBST, BZT shows a low Curie temperature. In order to decrease the phase transitiontemperature and increase the dielectric properties, Sr and Zr co-doped barium titanate（BSZT） nanoparticles were synthesized by solvothermal method under identicalpreparation conditions of Sr and the effect on microstructure and properties was discussed.The results show that the growth of grains was restrained, the Curie temperaturedecreases and broadened gradually. The degree of diffusion phase transition increaseswith increasing Zr content and the stability of dielectric constant-temperature increases.The reaction mechanisms of BSZT nanoparticles synthesized by solvothermal methodwere analyzed.4. The effect of Ca doped barium zirconate titanate on microstructure and dielectricproperties was investigated. The result shows that the shape changes from laminated sheetto cube，the dielectric loss decrease and the Curie peak becomes broadening in the rangeof temperature measurement and the stability of dielectric constant-temperatureincreases..