Cu取代对水滑石前驱物及其衍生氧化物性能的影响

恒定二价与三价阳离子比为3,采用共沉淀法制备不同Cu含量的系列水滑石前驱物,经过焙烧形成复合氧化物(CuO质量分数为0、5%、10%、15%、20%、30%、40% )材料.采用X射线衍射(XRD)、热重分析(TGA)、差示扫描量热(DSC)、程序升温还原(TPR)、傅立叶红外光谱分析(FTIR)等表征手段研究了Cu、Mg含量对材料前驱物和衍生复合氧化物物化性能的影响.结果表明,在CuO≤30%范围内可以形成结构完整的水滑石前驱物, CuO>40%时出现Cu(OH)2 杂相; CuO≤20% (质量分数)时,经高温焙烧可得到的均匀的复合氧化物,CuO>20%时出现CuO偏析.Cu、Mg含量对材料的热稳定性能有显著的影响,焙烧温度和组成决定了材料的还原性能.     

多自旋态离子Co替代诱导La2/3Ca1/3MnO3体系的输运反常

利用具有多自旋态的Co离子进行Mn位替代.制备了La2/3Ca1/3Mn1-xCoxO31(0≤x≤0.15)系列样品并研究了体系的结构和输运特性.结果表明,在替代范围内,样品呈现很好的单相结构,各晶格参数随替代量的增大而减小;Co替代导致体系出现电输运反常,具体表现为在居里温度Tc以下电阻-温度曲线的二次金属-绝缘转变(M-I)行为(双峰效应),且随Co替代量的增大,无论是高温峰还是低温峰,其峰值温度均向低温区移动;所不同的是,对Co替代样品而言,随外加磁场增加,高温峰值温度TPH向高温区移动,而低温峰值温度TPL.则保持不变,表现出磁场无关的特征;相应的峰值电阻率对Co替代和外加磁场表现出很强的依赖关系,随Co替代含量的增加,各峰值电阻率增加.而低温峰值电阻对Co替代更为敏感;对照样品磁特性测量结果,证明高温峰对应于未替代体系的M-I转变,低温峰对应的反常变化则与Co3 离子替代Mn4 后在体系中引入氧缺位和高的自旋态相关联.     

Adsorption Mechanism of Hydrogen on Boron-Doped Fullerenes

The C35BH-H2 complex and two other possible isomers, C34BCaH-H2 and C34BCbH-H2, are investigated using the local-spin-density approximation （LSDA） method. The results indicate that a single hydrogen molecule could be strongly adsorbed on two isomers, C34BCaH and C34BCbH, with binding energies of 0.42 and 0.47eV, respectively, and that these calculated binding energies are suitable for reversible hydrogen adsorption/desorption near room temperature. However, it is difficult for the H2 molecule to be firmly adsorbed on C35BH. We analyze the interaction between C34BCxH （x= a, b） and the H2 molecule using dipole moments and molecular orbitals. The charge analysis showed there was a partial charge （about 0.32e） transfer from 1-12 to the doped fullerenes. These calculation results should broaden our understanding of the mechanisms of hydrogen storage using borondoped fullerenes.     

毛细管电泳法测定PTA中BA、4-CBA和p-TOL含量

苯甲酸 (BA)、4 -羧基苯甲醛 (4 - CBA)和对甲基苯甲酸 (p- TOL)是对苯二甲酸 (PTA)产品的重要质量指标。本文用毛细管电泳法测定 PTA中 BA、4 - CBA和 p- TOL含量 ,加标回收率为 96 %— 10 6 % ,方法操作简便、快速、准确。     

Laser Micro-Hole Drilling of Soda-Lime Glass with Femtosecond Pulses

Using tightly focused femtosecond laser pulses, we have drilled micro-holes from the front and rear surface of soda-lime glass in ambient air. The machined holes have small aspect ratio or irregular inner walls. When the drilling is conducted from the rear surface in contact with distilled water, a good quality micro-hole with a high aspect ratio can be obtained. The corresponding formation mechanisms are investigated.     

Effect of High Resistance Phases on Metal—Insulator Transition of La0.67Ca0.33MnO3

The temperature dependence of resistivity ρ of YSZ doping composite of (1-x) La0.67Ca0.33MnO3 xYSZ and Y2O3 doping composite of (1-y) La0.67MnO3 yY2O3 is investigated,respectively,in a temperature range 77-300K,where the YSZ represents yttria-stabilized zirconia(8mol%Y2O3 92mol% ZrO2).Experimental results show that the YSZ doping level has important effects on both the metal-insulator(M-I) transition temperatures and zero field resistivity of the composites of (1-x) La0.67Ca0.33MnO3 xYSZ.However,the Y2O3 doping level has little effect on the M-I transition temperatures and the zero field resistivity of (1-y)La0.67Ca0.33MnO3 yY2O3 only increases slightly.The difference between the two types of composites may mainly results from the different distribution of high resistance phases at the grain boundaries and /or surfaces of La0.67Ca0.33MnO3 grains rather than the substitution of La^3 ions with Y^3 ions.     

Entangled States Used in Remote Information Concentration and Their Properties

We analyse a process of remote information concentration achieved by the W state. The result turns out to be neither as good as performed by the GHZ state nor as by the Smolin bound entangled state. Based on this particular phenomenon, the properties of the three entangled states are realized.     

内耗研究的历史评述

通过介绍几位在内耗领域的先驱研究者：C．Zener，葛庭燧，P．G．Bordoni，J．L．Snoek，评述了内耗研究的进展．也介绍了日本研究者的相关工作。     

Yb3+:YAG片状激光器的温度效应及金刚石窗口冷却设计

 基于准三能级速率方程分析了Yb³⁺:YAG 片状激光器的温度效应，结果表明随着激光介质的温度由300 K升高到400 K，激光器的储能提取效率由43%下降到26%。提出了利用热传导性能及优异的金刚石窗口对激光片的两端面进行冷却设计。模拟结果表明对掺杂11.6 %厚度为1.2 mm的激光片在泵浦功率密度为15 kW/cm²，重复频率为10 Hz的条件下，要将最高温度控制在可接受的范围内（比如320 K），周围冷却水的对流换热系数不应小于2 kW/(m²·K）。模拟结果还表明，在相同的热功率密度和冷却条件下，减小激光片的厚度同时增加抽运光的传输次数可以明显的降低激光片的温度。     

片状热容激光器热效应有限元分析

 基于激光介质的非均匀内热源模型,利用有限元数值方法,模拟计算了热容模式下高功率激光二极管阵列(LDA) 重复脉冲泵浦片状激光介质的瞬态温度分布和热应力分布及其波前畸变和应力双折射。结果表明:热容模式下,当增益介质不能够被全口径泵浦时,也会出现严重的热效应,介质的表面靠近边缘处会出现大的拉应力集中,介质表面的最大轴向位移和最大拉应力随泵浦光斑尺寸缩小而增大;而当全口径泵浦时,介质表面热形变大大减弱,较小的拉应力存在于介质内部,而且泵浦光斑和介质的几何形状对热分布有很大影响。结果还表明,介质片表面变形和热光效应是产生波前畸变的主要原因,而热应力双折射产生的附加相移与激光介质的切割方向有关,它对光束产生较大的退偏作用,从而影响激光器的输出性能。理论模型得到了实验结果的验证。