High-performance Barium Titanate Based Ptcr Ceramics

Barium titanate ceramics, which have been developed in several decades years, are a kind of new functional ceramics. At present, they have been one of the most important functional ceramics and used as the basic raw materials in the composition of ceramic capacitors. The research of preparation and properties of doped barium titanate has been a focal point in the field of inorganic nonmetal materials since the dielectric properties of barium titanate materials were discovered in the sintering process.However, the research of barium titanate and electric materials with high performance was began only in recent years in our country and there is a lot of work to do. In this paper, according to the preparation of BaTiO₃ - based PTCR ceramic materials with high performance, nanocrystalline BaTiO₃ - based PTCR powder and its ceramic materials were prepared using the synthesis method of sol-gel in one step and China-made raw materials. During the experiment, the influence of every doped element and sintering process on the properties of ceramic materials was analysed, and the powers and ceramics were characterized by TG-DSC, XRD and SEM.Firstly, the orthogonal experiment was successfully used to design and optimize components of PTCR ceramic materials. The influence of five factors including Ti/Ba, Mn, Y, Ca and Pb on ceramic materials was discussed by the orthogonal experiment.Secondly, doped experiments of four factors including Ca, Mn, Ti/Ba and Si have been completed. The influence of their contents and sintering process in the experiments on the properties of ceramic materials was discussed in detail. High performance BaTiO₃-based PTCR ceramic materials with low resistivity were finally obtained.In addition, a try of using tributyl borate(B) as dopant was tested, and the influence of that on the properties of ceramic materials was discussed.Finally, high performance PTCR ceramic material with a curie temperature (T_c) of 100°C, a resistivity at room temperature( ρ_室) of ¹8Ω.cm, a temperaturecoefficient of resistivity (α₃₀) of ¹7%.°C^-1, a withstand voltage intensity(V_b) of>195V-mm"1 , a resistivity step ratio (pmax//?min) of > 106 , excellent overvoltagewithstanding and over-current withstanding was obstained by optimizing doped elements and sintering process.