Oxygen vacancy control of electrical,optical, and magnetic properties of Fe0.05Ti0.95O2 epitaxial films

High-quality Fe-doped TiO₂ films are epitaxially grown on MgF₂ substrates by pulsed laser deposition. The x-ray diffraction and Raman spectra prove that they are of pure rutile phase. High-resolution transmission electron microscopy (TEM) further demonstrates that the epitaxial relationship between rutile-phased TiO₂ and MgF₂ substrates is 110 TiO₂₂. The room temperature ferromagnetism is detected by alternative gradient magnetometer. By increasing the ambient oxygen pressure, magnetization shows that it decreases monotonically while absorption edge shows a red shift. The transport property measurement demonstrates a strong correlation between magnetization and carrier concentration. The influence of ambient oxygen pressure on magnetization can be well explained by a modified bound magnetization polarization model.     

ICP与吸收光谱测定LiNbO3, Zn:LiNbO3晶体中Cr3+离子的分布及有效分凝系数

应用坩埚下降法生长了掺杂Cr与双掺杂Cr，Zn的LiNbO3晶体。测定了掺杂晶体不同部位的吸收系数。用电感耦合等离子体原子发射光谱(ICP)法测定了Cr离子在LN晶体中的浓度，并计算了Cr离子在LiNbO3晶体中的有效分凝系数。研究结果表明：在单掺杂Cr的LiNbO3晶体中，随着Cr^3 掺杂浓度从0．1增加到0．5mol％时，其有效分凝系数从3．75减少到2．49，Cr^3 离子在晶体中的浓度分布差异逐步减少；ZnO的掺入能有效地减少Cr^3 的分凝系数，然而ZnO掺杂浓度从3增加到6mol％时，其有效分凝系数且从1．85增加到2．25。可从ZnO组分对Cr离子的排斥作用及Zn离子在LN晶体中随掺杂数量变化的分凝现象解释了产生Cr离子浓度及有效分凝系数变化的原因。     

基于灰度插值的条纹图像位移亚像素检测算法

基于光栅干涉条纹的位移测量系统,提出了一种基于灰度插值的条纹图像位移检测算法即灰度极值法.首先,对光学位移测量系统进行了介绍;其次,阐述了灰度极值算法的原理.为了验证算法,对光学系统条纹图像进行了软件仿真,并对其进行了亚像素级定位算法仿真,对比分析了传统图像相关法与光流法,得到了相对误差曲线,所提算法的精度为1.797...     

光子晶体定向耦合三波长功分器

以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行以一行耦合介质柱为间距的平行单模线缺陷波导.通过分析和研究光子晶体波导耦合结构的耦合和解耦合特性,发现在不同频率下耦合波导的耦合长度不同.利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合波导的耦合长度,设计了一种新型超微光子晶体波导耦合型三波长功分器,实现了归一化频率分别为0.369、0.394、0.435的光波的分束效果.采用时域有限差分法验证了该功分器具有很好的功率分配效果.本文结果有助于光子晶体新型滤波器、定向耦合器、波分复用器、偏振光分束器以及光开关等光子器件的研究.     

Graphene/Mo_2C heterostructure directly grown by chemical vapor deposition

Graphene-based heterostructure is one of the most attractive topics in physics and material sciences due to its intriguing properties and applications. We report the one-step fabrication of a novel graphene/Mo_2C heterostructure by using chemical vapor deposition(CVD). The composition and structure of the heterostructure are characterized through energydispersive spectrometer, transmission electron microscope, and Raman spectrum. The growth rule analysis of the results shows the flow rate of methane is a main factor in preparing the graphene/Mo_2C heterostructure. A schematic diagram of the growth process is also established. Transport measurements are performed to study the superconductivity of the heterostructure which has potential applications in superconducting devices.     

液态金属结构研究新进展

文章介绍了用内耗方法研究金属液态结构的新进展,发现了随温度变化金属液态结构发生不连续的变化,并经差热分析、X射线衍射等实验证实了这种变化.这对认知金属液态结构提供了新的实验依据.     

自适应光学系统控制效果分析的功率谱方法

用H-S 波前探测器得到校正前后波前相位时间功率谱, 分析了自适应光学控制系统对大气湍流扰动波前的时域校正效果。用这种方法比较了61单元自适应光学系统分别采用P-I 控制算法和Smith 纯滞后补偿控制算法对实际大气湍流扰动波前进行补偿实验时的校正效果。     

磁力平衡悬梁式液体界面张力仪的研制

液体界面张力系数是液体的重要物性参数之一,实现液体界面张力系数的精确测量具有重要的应用价值,所以我们以吊环法为基础开发出一套新型液体界面张力仪,该型仪器借助杠杆原理,利用霍尔式位移传感器以及永磁/电磁复合磁悬浮技术,通过对一个单摆式悬梁悬浮状态的监测和控制,将作用于金属吊环上的拉力适度放大并反映为电磁线圈的工作电流,进而实现液体界面张力的电法精确测量.所设计的仪器结构简单、测量精确、重复性好.     

两相流PIV粒子图像处理方法的研究

本文在单相PIV技术的基础上研究了两相流动PIV图像处理方法，采用摸板匹配法和灰度加权标定法对两相粒子进行了识别、区分和标定，采用灰度互相关法对区分后的单相粒子图像进行了处理，应用基于以上方法编制的Windows应用软件，首先对由美国Minnesota大学复杂流动实验室提供的两相流动粒子图片进行了处理，通过对比分析可见，应用本文所采用的方法能对两相粒子进行有效的识别和区分，然后以搅拌槽内液固两相流场为例对此方法进行了应用。     

A Two-Photon Femtosecond Laser System for Three-Dimensional Microfabrication and Data Storage

Utilizing the well-focused femtosecond laser with extreme high pulse intensity, we built a two-photon micro-fabrication and data storage system, which was introduced through several functional parts. Based on this homemade system, several three-dimensional microstructures were fabricated by two-photon polymerization, and three-dimensional data storage of six-layers was achieved by two-photon excitation with a photochromic material.