A Fast Mechanochemical Synthesis Of Nano-structured Ferroelectric Materials At Low Temperature

Since the discovery of ferroelectric material,Pb-containing materials,such as PZT,PLZT,PZN,PMN,play important roles in high technological field because of their excellent dielectric and electro-strictive properties.A conventional synthesis method is based on solid state diffusion starting from MgO,PbO and Nb₂O₅ at the high temperature(1200-1400K) for more than 48 hours.Since the solid-state reaction method has some drawbacks such as high reaction temperature,large particle size and limited degree of chemical homogeneity,many soft chemistry methods have been developed to synthesize Pb(Mg_1/3Nb_2/3)O₃ perovskite materials,such as chemical co-precipitation and sol-gel etc..Though these chemical solution processes can produce fine and homogenous particles,complicated process and expensive agents are the main demerits of the referenced ways.An easier,lower-cost and more environmental method of synthesizing fine and homogenous powders of Pb(Mg_1/3Nb_2/3)O₃ is required.One available choice may be the mechanochemical process,which can synthesize fine and homogenous particles directly from cheap raw materials.First we use normal mechanochemical process by planetary ball mill,which employs a mechanism of comminution and dispersion,and always produces an amorphous phase, materials treated by planetary ball mill can be changed into expected crystal products with the help of further annealing treatment at 900℃.According to our understanding of mechanochemical process,a new mechanochemical machine designed by Qiang Li was employed.Its main functions are compression and shearing instead of collision and comminution,and the rotating speed is not sufficient to describe the mechanochemical process directly,so we induce another factor-power,to explain the mechanochemical reactions,after a few hours milling,the yellow nano powders of PMN were obtained.We have study some impact factors of milling power, milling time and so on,and we have confirmed some parameters of synthesis process. Further,from the ensured parameter we succeeded in synthesizing BaTiO₃ and SrTiO₃ nano powders in the same method.Based on above results,we can say that our new mechanochemical method was an effectively to synthesize many kind of nano-structured ferroelectric material.