氢对PbZr0．5Ti0．5O3在氮氢混合气氛退火中铁电性能的影响

采用基于密度泛函理论的第一性原理,针对PbZr0.5Ti0.5O3无氧和含氢的顺电相和铁电相的二层超晶胞,分别计算了 Ti 沿 c 轴位移时体系总能量的变化、电子云密度分布和Ti-O、Zr-O和H-O的重叠布居数.结果表明,含氢铁电相的Ti-O键和Zr-O 键相埘无氢铁电相明显减弱,氢氧之间较强的轨道杂化使它们趋于形成共价键;晶格中氧氧键的钉扎效应使含氢情况下的顺电相能昔始终低于铁电相能量,说明氢的引入阻碍了PbZr0.5Ti0.5O3从立方顺电相到四方铁电相的相变,并推断其为含氧气氛退火过程中PbZr0.5Ti0.5O3铁电性能下降的主要原因之一.所得结果对于深入理解铁电材料在氮氢混合气氛退火后铁电件能下降的微观机制具有参考价值.     

Dynamic simulation on the preparation process of thin films by pulsed laser

An ablation model of targets irradiated by pulsed laser is established. By using the simple energy balance conditions, the relationship between ablation surface location and time is derived. By an adiabatic approximation, the continuous-temperature condition, energy conservation and all boundary conditions can be established. By applying the analytical method and integral-approximation method, the solid and liquid phase temperature distributions are obtained and found to be a function of time and location. The interface of solid and liquid phase is also derived. The results are compared with the other published data. In addition, the dynamics process of pulsed laser deposition of KTN (Kta_0.65Nb_0.35O₃) thin film is simulated in detail by using fluid dynamics theory. By combining the expression of the target ablation ratio and the dynamic equation and by using the experimental data, the effects of laser action parameters on the thickness distribution of thin film and on the thin film component characteristics are discussed. The results are in good agreement with the experimental data.     

对沈阳理工大学开展篮球选修课现状的调查分析

篮球运动是一项受到广大青少年喜爱的运动,在普通高校中得到广泛地开展。本研究主要利用文献资料法、问卷调查法、访谈法、数理统计等研究方法对沈阳理工大学学生篮球选修课的学习兴趣、学习动机以及篮球课中存在的问题进行调查分析,揭示了学生对篮球运动的兴趣特点和要求。提出在教学中除加强篮球技术教学外,应致力于传授篮球的基本理论知识,建立正确的体育观念,掌握篮球运动锻炼身体的方法,培养篮球实践的综合能力,为沈阳理工大学篮球课的教学提供了理论参考依据。