Room-Temperature Ferromagnetism of Co-Doped CeO2 Thin Films on Si（111） substrates

Using Co2O3 as the Co source, doped cerium oxide thin films with the composition of Ce0.97C00.03O2-δ （CCO） are deposited on Si（111） and glass substrates by pulse laser deposition technique. X-ray diffraction reveals that CCO films with （111） preferential orientation are grown on Si, while the fihn on glass is polycrystalline with nanocrystal. X-ray photoelectron spectroscopy shows that the （Jo displaces the （;e atom and exists in high spin state rather than low spin state, which contributes to the room-temperature ferromagnetism confirmed by vibration sample magnetometer. I~ilms on Si and glass are different in ferromagnetism, which is believed to be induced by different film microstructures. Based on these results, the possible ferromagnetism in this insulating film is discussed. Anyway, successful fabrication of CCO films with room-temperature ferromagnetism on Si substrates is of great importance in both technological and theoretical aspects.     

Electronic Structures of Wurtzite GaN with Ga and N Vacancies

The electronic band structures of wurtzite GaN with Ga and N vacancy defects are investigated by means of the first-principles total energy calculations in the neutral charge state. Our results show that the band structures can be significantly modified by the Ga and N vacancies in the GaN samples. Generally, the width of the valence band is reduced and the band gap is enlarged. The defect-induced bands can be introduced in the band gap of GMV due to the Ga and N vacancies. Moreover, the GaN with high density of N vacancies becomes an indirect gap semiconductor. Three defect bands due to Ga vacancy defects are created within the band gap and near the top of the valence band. In contrast, the N vacancies introduce four defect bands within the band gap. One is in the vicinity of the top of the valence band, and the others are near the bottom of the conduction band. The physical origin of the defect bands and modification of the band structures due to the Ga and N vacancies are analysed in depth.     

First-principles calculations for elastic properties of rutile TiO2 under pressure

This paper studies the equilibrium structure parameters and the dependences of the elastic properties on pressure for rutile TiO2 by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of density functional theory. The obtained equilibrium structure parameters, bulk modulus B0 and its pressure derivative B′0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C11, C33, C66, C12 and C13 increase, The variation of elastic constant C44 is not obvious and the anisotropy will weaken.     

蓝宝石火花塞

在如何提高火花塞的工作质量方面有多种方法,但是其中最重要的一个问题还没有得到解决,那就是火花塞工作的热学模型问题。理想的火花塞应该能在点火的瞬间被立刻加热,并且在接下来的电脉冲过程中迅速冷却,由此在热量的存储与散发之间取得平衡,以避免自点火。本文力图展示一种具有自动调节源于点火区域热流能力的火花塞,其技术的关键是顶部绝缘体材料,它是由蓝宝石单晶制作,而非传统的氧化铝陶瓷。     

超Ornstein-Uhlenbeck过程击中概率估计

本文首先通过布朗运动的时间和空间变换给出一类Ornstein－Uhlenbeck过程局部最大值分布的概率估计,然后研究相应的超Ornstein－Uhlenbeck过程的击中概率问题,并给出了它的一个上界估计.     

高温高密度氦的压缩特性及其结构的分子动力学模拟

用分子动力学方法和不同参数的指数 6势函数计算了T =30 4K的高密度氦的等温压缩线和能量分布 .给出了能精确描述高密度氦原子间相互作用的指数 6势函数优化参数 .并用优化的势函数计算了高密度氦T =30 0K和T =2 98K的等温压缩线 ,计算结果和实验值非常吻合 .进一步用优化的势函数模拟了高温高密度氦的状态方程及其结构 ,发现当把 ρ限定为 1 .6 0g /cm³ 时 ,其径向分布函数的第 2个峰将在 2 0 0 0～ 30 40K区间消失 ,表明此时发生了固 液相变过程 .     

双曲空间H~2(-1)上预定高斯曲率的共形形变

本文研究预定高斯曲率时H~2（－1）上共形高斯曲率方程的可解性和不可解性,给出H~2（-1）上旋转对称函数是其上共形高斯曲率的一个充分条件,特别地证明了：H~2（-1）上每个非负的旋转对称函数都是其上无穷多个共形度量的高斯曲率     

碳水混合物相互作用势及混合法则的实验研究和理论探索

 利用二级轻气炮加载技术研究了碳水混合物的冲击压缩特性。研究发现：冲击压力p低于19.0 GPa时,石墨与水混合物冲击压缩特性明显不同于金刚石与水混合物的冲击压缩特性;p大于23 GPa后,它们的特性十分接近;当p为52.9 GPa时,石墨与水混合物表现出反常的冲击压缩特性,压力增加而体积出现膨胀,这与高压下碳与水发生化学反应产生气体相关。还对碳水混合物的相互作用势及混合法则的选取进行了讨论。     

液态甲烷的高温密度物态方程理论研究

 采用热力学统计理论研究了液态甲烷在高温高压下分子分解反应特点及该体系的物态方程。着重讨论了体系中CH₄-H₂分子间有效势对体系化学反应平衡及物态方程的影响,并根据实验Hugoniot点(p_H, V)优化确定出其exp-6势函数中的参数值。该势函数的排斥部分值比理想混合条件下Lorentz-Berthelot规则给出的势函数值低约50%,预示着高压下CH₄和H₂之间存在着某种亲合性。用该势函数计算得到的p-T线与现有的两个实验点符合很好。还讨论了CH₄-H₂之间的有效作用势参数对CH₄分子冲击离解度（x）的影响。     

CALCULATION OF HIGHLY EXCITED VIBRATIONAL ENERGY LEVELS OF CH3CN MOLECULE BY NON-LINEAR QUANTUM THEORY

A three-parameter nonlinear dynamical model, i.e., the quantized discrete self-trapping equation, was used to calculate the highly excited CH stretching vibrational energy levels of liquid phase CH₃CN molecule in the electronic ground state up to n=7. The calculated results show that the experimental energy levels can be well described by the model.