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.

基于spike-and-slab先验分布的贝叶斯变量选择方法

针对超高维数据,提出一种基于spike-and-slab先验分布的超高维线性回归模型的贝叶斯变量选择方法。该方法继承了弹性网方法和EM算法的优点,以较快的收敛速度来获得稀疏的预测模型。特别地,针对系数的spike-and-slab先验分布设置上,该方法允许系数从不同坐标借力、自动适应已知数据的稀疏信息以及进行多重调整。通过与常用方法的比较,证明了该方法的准确性和有效性。