Preparation And Studies On Structure And Properties Of Microcystalline Thermal-sensitive Ceramic Material Based On BaTiO₃

The ceramics preparaed by barium titanate which has an excellent PTC effect and curie temperature can be flexibly adjusted.It is widely used in electronic communications,computers,automotive industry,household appliances,high-speed rail and other industries.With the rapid development of electronic technology,electronic components toward the trend of miniaturization,integration,high power development.This is also a higher demand for heat-sensitive ceramics,the traditional heat-sensitive ceramics are faced with difficult to miniaturization,poor resistance to voltage and large current performance and other issues,reducing the grain size of barium titanate-based semiconducting porcelain is an effective way to solve these problems.In order to reduce the grain size,this paper takes barium carbonate and titanium dioxide as raw material,the effects of impurities and processes on the electrical properties and microstructure of barium titanate semiconducting porcelain were studied.The main research is as follows:Studied the semiconducting mechanism of barium titanate-based ceramic materials,it is found that donor is a key factor in semiconductivity of barium titanate ceramics,within a certain range with the donor content increases,the ceramic grain size decreases,the room temperature resistivity increased rapidly.Do ac impedance spectroscopy analysis found that the resistance of the ceramic material consists of grain resistance and grain boundary resistance together,grain boundary resistance plays a leading role.The mechanism of acceptor,Curie point mobile agent,Ca,liquid relative to barium titanate semiconducting porcelain was studied.It is found that the proper amount of donor doping can significantly improve the PTC effect of barium titanate semiconducting porcelain,curie point mobile agent can not only change the Curie temperature of the material also has a great impact on its microstructure,appropriate amount of Ca and liquid phase can make barium titanate semiconducting porcelain grain growth fine,uniform,dense.By studying the effect of these impurities on the properties of ceramic materials,determine the appropriate doping amount for each impurity,Get the best formula.On the basis of the best formula,the effects of calcination temperature,sintering temperature and holding time on the electrical properties and microstructure of barium titanate semiconducting porcelain were studied.High calcination temperature will reduce the grain size of the ceramic,high sintering temperature and long holding time will increase the grain size of ceramic materials,while the electrical performance also has a great impact.The optimum calcination temperature and sintering curve were selected by experiment.Through the study of impurities and technology,prepared with good microstructure and electrical properties of barium titanate-based microcrystalline thermal ceramics,its room temperature resistivity is about 10~4?·?,the curie point was 180?,resistivity jumps of 10~3and average grain size reaches about 4?m.