Phase Transition and High Piezoactivity of Sb Doped （Na0.53K0.435Li0.035）Nb0.94Ta0.06 O3 Lead-Free Ceramics

Lead-free piezoelectric ceramics with the composition of （Na0.53K0.435Li0.035）Nb0.94Ta0.06 O3 （NKLNST） axe synthesized by a conventional solid-state sintering process. An MPB-like region between orthorhombic and pseudocubic phases is found in this system. The density, piezoelectric and dielectric properties axe enhanced greatly in this region. A composition （Na0.53K0.435Li0.035）（Nb0.94Ta0.06）O3 is found to have excellent electrical properties： d33 = 320pC/N, kp= 49% and kt =43%, as well as relatively low loss, tan δ=4.2%, and high relative density higher than 96%, which indicate that this ceramics is a promising lead-free piezoceramics replacing for lead zirconate titanate.     

光指针式微小位移测量仪

光指针式微小位移测量仪巧用光路将微小的位移量放大,从光指针终端的标度盘上可以直接读取实际的位移数值.     

调谐半导体激光吸收光谱自平衡检测方法研究

可调谐半导体激光吸收光谱技术(TDLAS)是利用半导体激光器的波长调谐特性,扫描待测气体特征吸收线,从而获得待测气体的浓度信息。基于可调谐半导体激光吸收光谱的自平衡检测方法能够有效地消除激光器光强波动等共模噪声和其他同性干扰的影响。实验表明自平衡检测方法可以获得较理想的结果,检测限低于体积比1.2×10-6,与直接吸收光谱法相比降低了一个数量级。自平衡检测电路简单,自带的电子增益补偿机制能够自动进行平衡探测,该方法不用加信号调制和锁相放大器,直接探测待测气体的吸收光谱,从而降低成本,减小系统装置体积,易于集成为便携式痕量气体检测仪。     

两种气液两相流模型的应用和比较

本文应用MUSIG模型[1]和均一直径模型对某溶液堆台架模型堆芯内气液流动传热进行了数值模拟.在MUSIG模型中堆芯内离散相气泡被分为5组不同直径的气泡,用于分析堆芯内气泡的流动变化和大小分布,采用Luo and Svendsen[2]和Prince and Blanch[3]模型描述不同直径气泡组间的破裂和聚合.在均一直径模型中,堆芯内的气体被考虑为同一直径的组分,并且不考虑其破裂与聚合现象.计算得到采用两个模型的模拟结果并且对其进行了对比研究.结果显示应用MUSIG模型的计算结果与台架实验结果吻合更好.     

绕Hydronautics水翼空化云流动的实验研究

采用高速全流场显示技术和DPIV对空化水翼近壁处的空化云流动形态和运动机理进行了讨论.结果表明:绕Hydronautics翼型的空化云运动是一个准周期性过程:稳定空泡团初生在翼型前部,向翼型后部发展布满整个翼面,在翼型后缘出现汽泡团旋涡,伴随反向运动,最终向下游脱落.当前条件下空泡团旋涡脱落周期约为74 ms.空化区与主流区的交界面上存在较大的速度梯度,一组对涡出现在翼型尾部处交界面上.此外,采用以空泡为示踪粒子的DPIV能够对空化流动流速分布进行有效测量.     

Photoluminescence Property of Co3O4 Nanowires

Co3O4 nanowire arrays are fabricated by electrodeposition with following heat-treatment in atmosphere ambient. Photoluminescence is investigated at 295K. In the experiment, when increasing the excitation light wavelength from 260 nm to 360 nm, two kinds of emissions corresponding to the increasing excitation light wavelength are observed. One of them alters the excited emission position, another keeps its emission position. The distinct behaviour of excited emissions related to the increasing excitation wavelength indicates that the mechanism of them must be different. According to the experimental comparison and first-principle calculation, the two kinds of emissions are discussed.     

Density functional theory study on LaNi4.5Al0.5 hydride phase： electronic properties and sites occupation＊

In this paper the crystal structure, electronic structure and hydrogen site occupation of LaNi4.5Al0.5Hy hydride phase （y = 5.0, 6.0） have been investigated by using full-potential linearized augmented plane wave method. The hydrogen atoms were found to prefer the 6m, 12o and 12n sites, while no 4h sites were occupied. A narrowed Ni-d band is found due to the lattice expansion, the total density of states at EF increases with y, which indicates that the compounds become less stable. The interaction between Al and Ni, H plays a dominant role in the stability of LaNi4.5Al0.5 hydride phase. The smaller the shift of EF towards the higher energy region, the more stable the compounds will be. The obtained results are compared with experimental data and discussed in the light of previous works.     

Light Irradiation through Small Particles and Its Applications for Surface Nanostructuring in Near Field

We investigate the light scattering through small particles and its applications in nanostructuring, such as nanobumping, nanopatterning and dry laser cleaning. The theoretical calculation based on Mie theory provides an exact solution for sphere cavity resonance and plasmon resonance, which are two mechanisms for dielectric and metallic particles assisted surface nanostructuring in near field. The experimental results indicate that nanobumps on glass surface and subwavelength holes array on silicon surface can be formed without cracks with the self-assembly of 1 μm silica particle mask under laser irradiation. It is also found that the scattering wave by 40 nm gold particles can propagate 200 times away in terms of particle radius as recorded by photoresist under the UV light irradiation. Meanwhile, dry laser cleaning of 40nm gold particle on silicon wafer is demonstrated at plasmonic resonance frequency. The total cleaning efficiency is estimated to be 80%.     

QUASILINEAR-ADDITIVE PROPERTIES AND APPLICATIONS

In this article, the authors study some basic properties of the so-called quasilinear- additive functions, and some applications to the special functions of quasiconformal analysis are specified.     

稀土—铱—锑合金热电材料的结构与量子化学计算研究

应用离散变分Xa量子化学计算方法，研究了IrSb3，Ir4NdGe3Sb9和Ir4SmGe3Sb9三个skutterudites的组成、结构、化学键和热电性能之间的关系。对Ir4NdGe3Sb9和Ir4SmCe3Sb9，用多个模型研究了稀土元素振动的结构。计算结果表明，稀土原子靠近Ge原子的模型比靠近Sb原子的模型更为稳定，热导率也较低。Ir4NdGe3Sb9的共价键比Ir4SmGe3Sb9弱，Ir4NdGe3Sb9和Ir4SmCe3Sb9的共价键又比IrSb3弱，与热导率的实验测量结果一致。