The Study On Synthesis Of Barium Strontium Titanate (Ba_0.7Sr_0.3TiO₃) Pyroelectricty Cermaic Materials

Barium strontium titanate (Ba1-xSrxTiO3, BST) ceramics have higher pyroelectric efficient, higher dielectric constant and lower dielectric loss than other common pyroelectric materials, So BST ceramics have been widely applicated in various kinds of electronic devices. It is a functional material with a bright future. As modern electronic ceramic is developed toward miniaturization,high precision and high reliability, higher and higher requirement is brought forward for the purity,the grain size,shaping and agglomeration characteristics of the barium strontium titanate powder.This paper adopts the Pechini and conventional sol-gel with four different preparing systems as the optional method to prepare the nano powder of barium strontium titanate, comparing the merits and faults of varies of chemical methods. The paper has made the TG/DSC/DTA analysis, XRD analysis and SEM analysis of the powder prepared in these methods. The result reveals that the powder of barium strontium titanate prepared by the Pechini and conventional sol-gel method can satisfy the requirements of such aspects as the homogeneity of the chemical compositions,the size and distribution and the morphology of the grains. From the result it can be known that the powder prepared by the method of sol-gel adding dispersing agent in the system of acetic acid has the characteristic of small size(the diameter is about 70nm), the sizes evenly distributed and very little agglomeration, thus it is a very promising method for preparing powder.This paper also addresses the characteristics of nano-powders used Gelcasting process, with Ba0.7Sr0.3TiO3 nano-ceramic powder as raw materials,with MBAM and AM for the monomer and crosslinking agent dubbed the concentration of 15% of the premixed solution, Configuration of solid content of 45% of the slurry by adding 1.0wt% of PMAA-NlI4 dispersant, for Gelcasting, after drying, binder and firing process to produce dense ceramic BST. And through appropriate Mn doping, significantly reducing material at room temperature dielectric loss. In Mn-doped volume of 0.5 at% and 0.7at%, sintering temperature of 1280°C Preparation of the samples, to achieve better performance of pyroelectric ceramics, near the Curie temperature, The pyroelectric coefficient of 4.0 cm×10-8C -2k-1 above, the detection rate of the corresponding value reached 5.0×10-5 Pa-1/2 above,dielectric loss less than 0.5% ,dielectric constant of about 3500.