LNO薄膜的射频磁控溅射制备及其电学性能与红外吸收性能

用磁控溅射法在Si（111）基片上以不同溅射功率沉积LaNiO3（LNO）薄膜,基片温度370℃,对沉积的薄膜样品进行快速热退火处理（500℃,10min）。使用电感耦合等离子体原子发射光谱（ICP-AES）精确测量不同溅射功率沉积的LNO薄膜退火前后的组分情况。分析发现：LNO薄膜经退火处理后,其中的Ni／La的比值随着溅射功率增大而越接近理想比1：1,其导电性能也越好。另外,我们以相同工艺制备了不同厚度的LNO薄膜顶电极,四探针电阻测试仪和红外椭圆偏振光谱仪测试其电学与红外吸收性能,实验发现：（1）LNO薄膜的电阻率随膜厚的增加而降低,在大约300nm厚时略又有增加趋势;（2）LNO薄膜的红外吸收系数随其厚度的增加而增加,且随红外波长的增大而减小。     

含压电层的功能梯度柱壳的自由振动分析

基于三维弹性理论,导出了带有压电层的圆柱形梯度壳的动力学方程以及相应的边界条件,用幂级数展开法得到了求解该圆柱形梯度壳自由振动的三维精确公式．通过实例模型求解了该壳体的自由振动的固有频率;分析了不同电学边界条件对壳体的振动频率的影响。结果可评估各种近似理论解和数值解的正确性。     

电梯轮轨耦合高频振动计算模型研究

电梯导轮和导轨相互作用产生的高频振动是电梯噪音的主要来源之一,本文基于导轨、导轮和电梯框架等各柔性构件的频响函数,建立了耦合振动系统的频域计算模型。分析了导轨表面粗糙度、导轮偏心和扁疤等激励对电梯高频振动的影响。通过与实测数据进行比较．验证了计算模型的有效性．从而为电梯的减振降噪设计提供了有用的分析工具。     

FeMn掺杂AlN薄膜的制备及其特性研究

采用直流磁控共溅射技术, 以Ar与N₂为源气体, 硅片为衬底成功地制备了Fe, Mn掺杂AlN薄膜. 利用X射线衍射和拉曼光谱研究了工作电流、靶基距离等工艺参数的改变对薄膜结构的影响. 利用扫描电子显微镜和能谱分析仪对薄膜的表面形貌和组成成分进行了分析. 利用振动样品磁强计在室温下对Fe, Mn掺杂AlN薄膜进行了磁性表征. Mn掺杂AlN薄膜表现出顺磁性的原因可能是由于Mn掺杂浓度较高, 在沉积过程部分Mn以团簇的形式存在, 反铁磁性的Mn团簇减弱了体系的铁磁交换作用. Fe掺杂AlN薄膜表现出室温铁磁性, 这可能是AlFeN三元化合物作用的结果. 随着Fe 掺杂AlN薄膜中Fe原子浓度从6.81%增加到16.17%, 其饱和磁化强度M_s由0.27 emu·cm^-3逐渐下降到0.20 emu·cm^-3, 而矫顽力H_c则由57 Oe增大到115 Oe (1 Oe=79.5775 A/m), 这一现象与Fe离子间距离的缩短及反铁磁耦合作用增强有关. 关键词： 直流磁控共溅射 氮化铝薄膜 结构 磁性     

高频燃烧红外吸收光谱法测定碳酸钴中的硫

采用高频燃烧红外吸收光谱法测定碳酸钴中的硫,在测定过程中先将样品进行灼烧处理,并选用纯铁和钨助熔剂熔样,解决了水分干扰和样品熔解不完全的问题。方法可以准确测定碳酸钴中质量分数为0.001%~0.01%的硫,加标回收率为98.4%~101.4%,相对标准偏差RSD为2.8%~6.3%。     

环境温度影响下基于LSTM神经网络识别结构损伤

环境温度的改变会引起模态参数的变化,其变化程度会掩盖或部分掩盖损伤引起的变化量,导致结构健康监测系统发出假阳性或假阴性的误判,因此,消除温度效应是提高损伤识别精度的关键。本文基于LSTM神经网络提出了一种环境温度影响下识别结构损伤的方法。充分利用LSTM神经网络的非线性映射优势,建立多元温度-模态频率的相关模型,在此基础上采用数据标准化方法消除温度效应,并结合控制图判断模态频率异常变化以确定损伤状况。最后将所提方法在数值模型和实际桥梁中加以应用,结果表明,方法能够有效消除温度效应;结合控制图能识别损伤时刻,并具有一定的抗噪性;在实桥数据分析中仍能表现出较好的损伤敏感性。     

Analysis of the growth of RF sputtered ZnO thin films using the optical reflective second harmonic generation

Reflective second harmonic generation (RSHG) is used to analyze the growth condition of poly crystal zinc oxide (ZnO) film with a c-axis orientation, grown on the Si substrate by RF magnetron sputtering technique. It elucidates physical phenomena exhibited by growing ZnO thin films. Connecting with analytical results of the characteristic parameters derived from the X-ray patterns and SEM images, the relationship between the RSHG intensity and the substrate temperature reveals that the effect of the grain boundaries is the domination of the RSHG mechanism. The inclined structures of ZnO films on the Si substrate are explained with reference to these RSHG patterns.     

Physical Properties of Zinc Oxide Films Prepared by dc Reactive Magnetron Sputtering at Different Sputtering Pressures

Thin films of zinc oxide were deposited by dc reactive magnetron sputtering onto glass substrates held at a temperature of 663 K and oxygen partial pressure of 1x10^‐3 mbar, and at different sputtering pressures in the range 3x10^‐2 ‐ 10x10^‐2 mbar. The effect of sputtering pressure on the structural, electrical and optical properties of the films were systematically studied. The films were polycrystalline in nature with preferred (002) orientation. The temperature dependence of Hall mobility indicated that the grain boundary scattering of the charge carriers are predominant in these films. The films formed at a sputtering pressure of 6x10^‐2 mbar showed a low electrical resistivity of 6.9x10^‐2 Ohm cm, optical transmittance of 83% with an optical band gap of 3.28 eV.     

Quantum Chemical Calculations and Experimental Studies on 2,3-Diphenyl-tetrazole-5-thione

1 INTRODUCTION Many substituted tetrazoles show a variety of interesting properties. For instance, they exhibit certain types of physiological activity by affecting the nervous system in a number of ways[1]. They are commonly used as good weed killers in…     

A frequency accurate spatial derivative finite difference approximation

We present a method for designing spatial derivative approximations that achieves a priori accuracy in the spatial frequency domain. We use a general, average value approximation with undetermined coefficients together with a set of constraints that ensure convergence and consistency to formulate a constrained optimal fitting problem. These constraints lead to a linear matrix formulation. We apply the method to the design of spatial approximations for simulating equations with wavelike solutions using both an explicit central difference approximation (which has no phase error) and an upwind design where the level of dissipation can be specified by the designer. © 1997 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 13: 549–560, 1997