Enhancing the thermal conductivity of polymer-assisted deposited Al2O3 film by nitrogen doping

<正>Polymer-assisted deposition technique has been used to deposit Al₂O₃ and N-doped Al₂O₃（AlON） thin films on Si（100） substrates.The chemical compositions,crystallinity,and thermal conductivity of the as-grown films have been characterized by X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）,and 3-omega method,respectively. Amorphous and polycrystalline Al₂O₃ and AlON thin films have been formed at 700℃and 1000℃.The thermal conductivity results indicated that the effect of nitrogen doping on the thermal conductivity is determined by the competition of the increase of Al-N bonding and the suppression of crystallinity.A 67%enhancement in thermal conductivity has been achieved for the samples grown at 700℃,demonstrating that the nitrogen doping is an effective way to improve the thermal performance of polymer-assisted-deposited Al₂O₃ thin films at a relatively low growth temperature.     

Al(Ⅲ)盐水解聚合过程中Al5和Al9的制备及初步表征

采用铝粉、水合氯化铝和水为原料,通过调整反应温度、原料配比及溶液碱化度,经蒸发、结晶制备了铝盐水解聚合产物中的2种中间产物,即水合氯化五聚铝AlCl3·4Al(OH)3·7.5H2O和水合氯化九聚铝2AlCl3·7Al(OH)3·18H2O分别采用粉末XRD物相分析、化学分析和IR光谱对其进行了表征. 以化学分析为主要监测手段,对AlCl3·4Al(OH)3·7.5H2O和2AlCl3·7Al(OH)3·18H2O的形成过程进行了研究. 结果表明,随温度的变化反应基本上是一个可逆的过程,75 ℃是AlCl3·4Al(OH)3·7.5H2O和2AlCl3·7Al(OH)3·18H2O析出的最佳温度,该温度下产物的结晶状态良好,其纯度分别可达99.57%和88.68%.     

Estimating optical lattice alignment by RF spectroscopy

A method that uses radio frequency (RF) spectroscopy to evaluate the alignment of an optical lattice is proposed and demonstrated. A one-dimensional (1D) optical lattice is applied along the long axis of a cigar-shaped Bose-Einstein condensate (BEC) in a magnetic trap. The RF spectra of condensates with and without the optical lattice are analyzed, measured, and compared with the condition in which the lattice is misaligned with the BEC. The proposed method greatly optimizes the optical alignments of the lattices.     

受扰不确定混沌系统的双路组合函数投影同步

研究了具有未知参数和外界扰动的多个混沌系统之间的双路组合函数投影同步问题.首先给出了由四个混沌驱动系统和两个混沌响应系统组成的双路组合函数投影同步系统的定义,然后以Lyapunov稳定性理论和不等式变换方法为分析依据,设计了鲁棒自适应控制器和参数自适应律,使得两路同步系统中的响应系统和驱动系统按照相应的函数比例因子矩阵...     

球磨La2Mg17+x％Ni(x=50,100,150,200)复合贮氢合金的电化学性能研究

研究了球磨制备的La2 Mg17+x％Ni(x =50,100,150,200)复合贮氢合金的电化学性能.XRD分析表明:随着Ni含量的增加,复合合金的晶体结构逐渐转变为非晶结构.电化学测试显示:球磨制备的La2Mg17+x％Ni复合贮氢合金在首次循环后即可达最大放电比容量,合金具有较好的活化性能;复合合金的放电比容量也随Ni粉加入量的增加而增大.在经过60h球磨后制得的非晶态的La2 Mg17+ 200％ Ni复合贮氢合金,其303 K下放电比容量为353.1 mAh·g-1.电化学放电比容量的提高应归因于非晶结构的形成以及Ni粉对表面状态的改变.     

Stabilized DFB laser system with large tuning range

We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically.This laser system consists of two distributed feedback(DFB) lasers, one of which is reference and locked to the D2 line of ~(87)Rb, the other laser is a slave that is locked to the reference laser via a loop servo. We measured the frequency of the beating signal of the two lasers and generated an error signal, which controlled the frequency of the slave laser to close the loop. We compressed the fluctuation of the beating signal's frequency to less than 1 MHz.Furthermore, the system can also automatically determine and control whether the slave is red detuned or blue detuned to the reference. The dimensions of our laser system are about 15 cm × 20 cm × 10 cm. This kind of laser system can be applied in many important applications, such as atomic interferometer and cold atomic clock.     

LED用Sr_((1-1.5x))Mo_(0.8)Si_(0.2)O_(3.8)∶Eu_x~(3+)红色荧光粉的制备及其荧光性能

通过高温固相法合成了LED用红色荧光粉Sr(1-1.5x)Mo0.8Si0.2O3.8∶Eu3x+(x=0.1,0.2,0.3,0.4,0.5)。通过XRD、激发光谱和发射光谱测试了材料的物相组成以及发光性能。x=0.1样品的XRD谱与JCPDS 08-0482(SrMoO4)的标准卡片相同。Eu3+代替晶格中Sr2+的位置成为发光中心。随着Eu3+含量x的增加,593 nm处的5D0-7F1跃迁和614 nm处的5D0-7F2跃迁发射强度会相互转换:当x≤0.4时,以磁偶极5D0-7F1跃迁为主,发射橙色光;而当x=0.5时,以电偶极5D0-7F2跃迁发射为主,发射红光。可能是过量掺杂的Eu3+离子,只能存在于晶格空位形成缺陷,无法占据SrMoO4中Sr2+的格位中,Eu3+在晶格中占据非对称中心的格位,导致电偶极跃迁变成允许跃迁,从而增加了5D0-7F2跃迁,减弱了5D0-7F1跃迁。因此,可以通过调节激活剂的含量获得不同发光色的荧光粉。Eu3+掺杂的硅钼酸锶体系,614 nm激发下,在368 nm处出现宽的基质吸收峰和467 nm处7 F0-5 D2的跃迁峰,且这2处的吸收峰在x=0.5时比x=0.4时...     

纳米Ce_(1-x)(Fe_(0.5)La_(0.5)x)O_(2-δ)固溶体的水热合成及光谱分析

采用水热方法合成Ce1-x(Fe0.5La0.5)xO2-δ固溶体。利用X射线衍射技术(X-ray diffraction tech-nique,XRD)表征样品的相结构,并对固溶体的晶胞参数进行拟合,通过紫外可见漫反射光谱(UV-Vis dif-fraction spectrum)及拉曼光谱(Raman spectrum)表征其电子跃迁性能及由于双离子掺杂所引起的一系列掺杂效应。XRD结果表明,Ce1-x(Fe0.5La0.5)xO2-δ固溶体为CeO2立方萤石结构,当掺杂量增加到x=0.30时出现了微弱的Fe2O3杂相衍射峰;讨论了两种离子在晶格中不同的取代位置。晶胞参数随着掺杂量的增大而逐渐增大,当掺杂量达到x=0.18后保持基本不变。紫外漫反射光谱表明,随着掺杂量的增大,固溶体的带隙吸收边红移,即能隙逐渐减小,Fe离子在CeO2晶格中表现为+3价。Raman光谱F2g振动峰位逐渐向低波数方向移动,同时振动峰逐渐宽化,进一步证明了掺杂离子的影响效应。     

水解聚合铝溶液中Al5和Al9的制备及初步表征

以相图理论为指导,采用铝粉、水合氯化铝和水为原料,创造氯化铝不断水解的条件,通过调整反应温度、原料配比及溶液碱化度,经蒸发、结晶制成了铝盐水解聚合产物中的两种中间产物：水合氯化五聚铝AlCl3•4Al(OH)3•7.5H2O和水合氯化九聚铝2AlCl3•7Al(OH)3•18H2O,分别采用粉末XRD物相分析、化学分析和IR对其进行了表征.以化学分析为主要监测手段,对AlCl3•4Al(OH)3•7.5H2O和2AlCl3•7Al(OH)3•18H2O形态过程进行了研究,结果表明,温度对于产物的行成及性能有很大的影响,并且反应随温度的变化基本上是一个可逆的过程,同时,实验表明 75℃为AlCl3•4Al(OH)3•7.5H2O和2AlCl3•7Al(OH)3•18H2O析出的最佳温度,该温度下产物的产率较高且结晶状态良好.     

Y2O3双掺杂Eu3+,Tb3+的光谱性能及能量传递过程

采用溶胶凝胶法制备不同配比的Y2O3∶Eu3+、Y2O3∶Tb3+和Y2O3∶Eu3+,Tb3+荧光粉.并通过XRD、SEM和激发、发射光谱对其结构和发光性能进行了研究,用能级图解释了激活剂之间的能量传递关系.结果表明,材料结晶良好,粒度分别为20、31nm和17nm左右,样品形貌类似片状结构.(Y110Eu)2kO3和(Y110Tb)2kO3配比时相对发光强度最高.而共掺杂时,存在着强烈的Eu3+向Tb3+的能量转移,导致红色发光强度的降低而敏化了绿光和蓝光的发射.分析可知,除了激活剂的含量对发光性能有强烈的影响之外,不同的激发波长对体系混合光的形成有很大的影响.当在305nm的激发波长下,可以得到红绿蓝混合光,实现了通过一种荧光粉的激发,发射出近白色的光.为改变灯用三基色荧光粉的组成并降低成本奠定了有利的实验基础.