Study on the Microstructure and Dielectric Properties of Barium Strontium Titanate Thin Films Prepared by Sol-gel Method

Sr05Ba0.5-xBixTiO3 （BST） thin films were fabricated on a Pt/SiO2/Si substrate by the sol-gel method. Then follows an investigation of the influeoces of bismuth （Bi） on the microstructures and the dielectric properties of Sr0.5Ba0.5-xBixTiO3 （BST） thin films. The microstructures of the BST thin films were examined by the XRD and the TEM techniques. Tetragonal perovskite crystal grains were observed in BST thin films. Increasing Bi^3＋ doping ration in BST will lead to decrease of the grain size. It is found that Bi^3＋ doping decreases the dielectric loss and improves the frequency dispersion of the BST thin films. Not only is compressed the peak of temperature-dependence of dielectric constant of Bi^3＋-doped BST thin films but also moves into the low-temperature region. Moreover, the average Curie tem- perature decreases gradually with the Bi^3＋ contents increasing.     

形状记忆高分子材料及其在航空上的应用前景

形状记忆高分子材料是８０年代出现的一种新型材料。本文介绍了形状记忆树脂的记忆原理、组成结构与记忆性能的关系及其在航空工业中的应用前景     

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本文以北京某机场为例，分析总结了道面应急整修，快速修补的具体作法，并就机场应急保障工作如何适应未来军事斗争的需要提出了建议，供同仁参考。