通过经典力学及流体力学基本原理,建立轨道模型对气流粉碎/静电分散相复合制备超微粉体中粉碎分散仓内颗粒的运动过程进行了数值模拟研究,揭示了气流粉碎/静电分散过程中粉体颗粒的运动规律。当荷电电压为20 k V,射流速度较低时粉体颗粒流存在准稳态层流流动现象;随着射流速度的提高,粉体颗粒转变为弥散分布,且分散性具有一定程度的提高;当荷电电压增大至60 k V时,仓内粉体颗粒的分散性有了进一步的提高,呈现出较好的均匀分散状态。研究结果表明,增大射流速度和荷电电压能够有效的提高制备过程中粉体颗粒的分散性,且后者效果更为明显。
A detailed theoretical study of the structural,elastic,and optical properties for Sr0.5Ca0.5TiO3is carried out by firstprinciples calculations.The band structure exhibits a direct bandgap of 2.08 eV at theΓpoint in the Brillouin zone.The bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio are derived based on the calculated elastic constants.The bulk modulus B=153 GPa and shear modulus G=81GPa are in good agreement with available experimental data.Poisson’s ratioν=0.275 suggests that Sr0.5Ca0.5TiO3should be classified as being a ductile material.Using the electronic band structure and density of states,we analyze the interband contribution to the optical properties.The real and imaginary parts of the dielectric function,as well as the optical properties such as the optical absorption coefficient,refractive index,extinction coefficient,and energy-loss spectrum are calculated.The static dielectric constantε1(0)and the refractive index n(0)are also investigated.
