Electronic structures and optical properties of HfO_2–TiO_2 alloys studied by first-principles GGA + U approach

The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content reaches more than 52.0 mol%, it presents rutile phase. So, we choose the three phases of HfO_2–TiO_2 alloys with different Ti content values. The electronic structures and optical properties of monoclinic, orthorhombic and rutile phases of HfO_2–TiO_2 alloys are obtained by the first-principles generalized gradient approximation(GGA) +U approach, and the effects of Ti content and crystal structure on the electronic structures and optical properties of HfO_2–TiO_2 alloys are investigated. By introducing the Coulomb interactions of 5 d orbitals on Hf atom(U_1~d), those of 3 d orbitals on Ti atom(U_2~d), and those of 2 p orbitals on O atom(Up) simultaneously, we can improve the calculation values of the band gaps, where U_1~d, U_2~d, and Up values are 8.0 eV, 7.0 eV, and 6.0 eV for both the monoclinic phase and orthorhombic phase, and 8.0 eV, 7.0 eV, and 3.5 eV for the rutile phase. The electronic structures and optical properties of the HfO_2–TiO_2 alloys calculated by GGA +U_1~d(U_1~d= 8.0 eV) +U_2~d(U_2~d= 7.0 eV) +U~p(U~p= 6.0 eV or 3.5 eV) are compared with available experimental results.     

硅纳米晶体薄膜热膨胀性质的分子动力学研究

基于Stillinger-Weber势对硅纳米晶体薄膜的热膨胀性质进行了分子动力学模拟。研究表明,硅纳米晶体薄膜表面层原子的二聚现象引起薄膜收缩,而原子之间的非和谐势能引起薄膜膨胀;在约400K以下的低温段,由于硅纳米晶体薄膜表面层原子发生二聚的原子数目随温度的升高而明显增多,而原子间非和谐势能很小,故此时二聚主导热膨胀性质,热膨胀系数为负;在高温段（约400K以上）,由于发生二聚的原子数目随温度升高不再显著地增加并渐趋于稳定,而原子间非和谐势能逐渐显著并主导热膨胀性质,故热膨胀系数为正。     

随机散斑投影粗粒反光表面图像采集方法

针对粗粒反光表面在一般光源照明条件下产生的局部反光问题,提出一种基于随机散斑投影的图像采集方法.以主动投影照明的方式在工件表面形成系列随机散斑图案,利用组图冗余信息抑制反光,生成光强均匀且高信噪比的融合图像.给出了随机散斑图畸变矫正方法,实现高效的密度均匀散斑投影.实验结果表明,所提方法很好地抑制了工件表面局部反光问题...     

荧光分光光度法直接测定盐酸异丙嗪片剂及注射液的含量

以０．０００１ｍｏｌ／Ｌ盐酸的溶剂,３０３ｎｍ为激发波和ｎｍ为发射波和散荧光分光光度法直接测定盐酸异丙嗪片剂及注射液中盐酸异丙嗪的含量。盐酸异丙嗪在０．１～１０．０μｇ／ｍＬ浓度范围呈良好线性。片剂及注射液的测定平均变异系数分别为０．３１％和０．４５％,回收率分别为９９．９％和９９．６％。     

羟基聚合铝晶体研究进展

羟基聚合铝的研究在环境化学中具有重要作用。自然条件下存在的无机单核铝本身具有毒性,而多核铝是比单核铝更毒的铝形态,它们很容易进入人体和植物产生毒害作用。因此,水解聚合铝形态研究一直是环境化学、地球化学和材料催化等众多研究领域的前沿热点课题。本文综述了在新环境材料开发中羟基聚合铝晶体研究的进展,对已获得表征的典型羟基聚合铝的结构特点进行了对比与评述,讨论了不同羟基聚合铝晶体的科学意义和应用价值。