稀磁半导体MnTe和CrTe的微观结构及电磁性能

基于密度泛函理论的VASP软件包,研究CrTe和MnTe晶胞的稳定性和电磁性能,并对比具有相同结构的CrTe和MnTe在稳定性和电磁性能方面的差异.结果表明,稳态的CrTe为具有NiAs结构的铁磁体,其闪锌矿结构(ZB)、纤锌矿结构(W)和岩盐结构(RS)为亚稳态结构,该亚稳态结构均为半金属性质.     

用低温化学气相沉积法大量制备单晶ZnO纳米线及其光致发光研究

在氩气气氛中,利用物理蒸发高纯Zn粉和SiO2纳米粉混合物的方法,控制温度在650℃时,获得了大量的六方相ZnO纳米线,直径约40nm,这和先前报道的制备ZnO纳米线的方法相比,温度降低了大约200℃-300℃.纳米线的生长过程中遵循气-固相生长机制.荧光光谱表明产物具有两个发射带,一个处于紫外波段,另一个处在绿光发射带.     

稀磁半导体Zn1-xNixO的制备、结构和磁性

用溶胶凝胶法合成Zn1-xNixO(x=0.03,0.05,0.10)系列化合物,利用X-射线衍射、磁强计对该系列化合物进行了结构和磁性表征.结果表明一定量的Ni离子进入ZnO的晶格中,形成稳定的纤锌矿型固溶体,空间群为P63 mc,晶胞参数随Ni掺入量稍有变化.该系列化合物表现为铁磁性,其居里-外斯温度随其成分稍有变化,并且表现出磁性离子的轨道磁矩并未完全淬灭.     

A Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous filler metal for improving the strength of Ti–6Al–4V alloy brazing joint

Ti_(50)Zr_(27)Cu_8Ni_4Co_3Fe_2Al_3Sn_3(at%) amorphous filler metal with low Cu and Ni contents in a melt-spun ribbon form was developed for improving mechanical properties of Ti–6Al–4V alloy brazing joint through decreasing brittle intermetallics in the braze zone. Investigation on the crystallization behavior of the multicomponent Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous alloy indicates the high stability of the supercooled liquid against crystallization that favors the formation of amorphous structure. The Ti–6Al–4V joint brazed with this Ti-based amorphous filler metal with low total content of Cu and Ni at 1203K for 900s mainly consists of α-Ti, β-Ti,minor Ti–Zr-rich phase and only a small amount of Ti_3Cu intermetallics, leading to the high shear strength of the joint of about 460 MPa. Multicomponent composition design of amorphous alloys is an effective way of tailoring filler metals for improving the joint strength.     

Influence of O_2/Ar ratio on the properties of transparent conductive niobium-doped ZnO films

Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300℃.The influence of O2/Ar ratio on the structural,electrical and optical properties of the as-deposited films is investigated by X-ray diffraction,Hall measurement and optical transmission spectroscopy.The lowest resistivity of 4.0×10-4 Ω·cm is obtained from the film deposited at the O2/Ar ratio of 1/12.The average optical transmittance of the films is over 90%.     

Comparative investigation of three types of ethanol sensor based on NiO-SnO2 composite nanofibers

NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.     

FeCuNbSiB多层非晶薄带的压应力阻抗效应研究

采用单辊法制备宽3.2 mm厚25μm的Fe73.5Cu1Nb3S i13.5B9非晶薄带,利用4294A型阻抗分析仪测试了非晶薄带的应力阻抗效应。结果表明:当测试频率较低时,双层Fe73.5Cu1Nb3S i13.5B9非晶薄带的应力阻抗效应较弱,随着频率的升高,双层Fe73.5Cu1Nb3S i13.5B9非晶薄带的应力阻抗效应出现了明显的增强;多层非晶薄带的应力阻抗效应比单层的小。     

2017年有机功能材料研发热点回眸

 从高效柔性有机半导体器件、高效有机太阳能电池、高效有机白光二极管、有机光伏器件的磁效应、有机自旋光伏器件设计等5个方面，盘点了2017年有机功能材料领域的重要研究进展；从有机电子学、有机光电子学和有机自旋电子学等多个角度，回顾了有机功能材料新奇的物理现象及原理；预测了该领域未来的发展方向。     

Structure evolution of Y2O3 nanoparticle/Fe composite during mechanical milling and annealing

Fe-25 wt% Y2O3composite powders have been fabricated by mechanical milling(MM) Fe powders of 100 μm in diameter and Y2O3nanoparticles in an argon atmosphere for the milling periods of4,8,12,24,36,and 48 h,respectively.The features of these powders were characterized by using X-ray diffraction(XRD),scanning electron microscopy(SEM),electron probe micro analyzer(EPMA) and transmission electron microscopy(TEM).The experimental results showed that the mean particle size and crystalline size of MM powders decreased with the milling time increasing.All the elements distributed homogenously inside the powders after 48 h of MM.The lattice constant of the matrix α-Fe kept constant with the milling time,and no solid solution took place during MM process.After 8 h of MM,the α-Fe in each powder became nanocrystalline.After 48 h of MM,Y2O3changes from nanostructure into amorphous structure,and the crystalline size of α-Fe further decreased to 10 nm.The Y2O3in the powders mechanically milled for 48 h kept the amorphous structure after being annealed at 400 1C,and starts to crystallize when the powders are annealed at 600 1C.The amorphous Y2O3contains a small amount of Fe,and crystalline FeYO3appears at 800 1C.     

第三代宽禁带功率半导体及应用发展现状

 近年来，以碳化硅和氮化镓为代表的第三代宽禁带功率半导体迅猛发展，已成为中国功率电子行业的研发和产业化应用的重点。抓住第三代宽禁带功率半导体的战略机遇期，实现半导体材料、器件、封装模块和系统开发的自主可控，对保障工业创新体系的可持续发展至关重要。在分析第三代宽禁带功率半导体重要战略意义的基础上，综述了其材料、器件研发和产业的发展现状，阐述了碳化硅及氮化镓器件在当前环境下的应用成果，剖析了第三代半导体行业存在的关键问题。建议在国家政策的进一步领导之下，发挥行业协会和产业联盟的桥梁和纽带作用，对衬底材料、外延材料、芯片与器件设计和制造工艺等产业链各环节进行整体支撑，引导各环节间实现资源共享、强强联合，上下游互相拉动和促进，形成一个布局合理、结构完整的产业链。