Detecting the micro-defects in the GaAs materials by time resolved emissions

The GaAs material is a major semiconductor material, and it has high electron transfer rate and direct transition energy band structure. The devices and inte-grated circuits fabricated on the GaAs substrates have a lot of advantages such as high speed information processing. Small perturbations in the manufacturing of GaAs materi-als can lead to defects. The defects in the GaAs materials can degrade the performance of materials. A new method is presented in this paper for detecting the micro-defects in GaAs materials by using time resolved emissions. In this method, the micro-defects in GaAs materials are detected by making use of the photon emission features of micro- defects. The strength of the emitted photons from the micro-defects is increased by applying the electric current or the periodic pulse signals to GaAs materials. The single-photon detector is used to detect the photon emissions of the micro-defects. The time resolved photon emissions and single-photon detection are used to record and compare the amounts of the emitted photons that come from the given regions of the normal GaAs materials and the defective GaAs materials. A lot of experimental results show that the micro-defects in the GaAs materials can be detected by using the method proposed in this paper.     

Computational diffusion kinetics and its applications in study and design of rare metallic materials

Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization and microstructure control during the processing of advanced metallic materials.This paper is to highlight recent progress of CDK in research with great focus on novel Ti and Zr alloys,which was largely performed in the authors’group.It ends with one representative example of the applications of CDK,coupled with CT,quantitative phase field,and three-dimensional(3D)statistical calculation,in designing the heattreatment schedule for the dual phase(αβ)Ti–6Al–4V alloys.     

建筑调湿材料吸放湿速度变化规律

实验测得了4种建筑材料样品在不同相对湿度条件下的平衡含湿量.将4种样品置于环境参数不同的恒温恒湿环境中进行12h吸湿12h放湿的吸放湿周期试验,测得了样品在各个环境条件下吸(放)湿过程中每小时的吸(放)湿量.实验结果表明,在样品所处环境相对湿度相同时,各实验样品的量纲为一的吸放湿速度是时间的同一幂函数.数值拟合得到了环境相对湿度分别为95%和75%时样品的量纲为一的吸放湿速度的表达式.给出了样品在恒温恒湿环境(风速在2.0m·s-1以下)中材料每小时吸放湿量计算值的相对误差.     

MnO/石墨烯复合材料的制备及其作为锂离子电池负极的研究

通过原位复合方法合成碳包覆MnO/石墨烯(C@MnO/GN)复合材料并探究其作为锂离子电池负极材料的电化学性能.扫描电子显微镜(SEM)以及透射电子显微镜(TEM)表征结果表明,MnO纳米颗粒(直径约为30~50nm)均匀分散在石墨烯片层上,且颗粒外面包裹一层厚度约为5nm的碳层.电化学测试结果表明该材料作为锂离子电池负极具有优异的倍率和循环性能.0.2和0.5A/g电流密度下,比容量分别为800和700mAh/g;10A/g电流密度下比容量仍能保持在372mAh/g;当电流密度调回0.5A/g时,其比容量仍能恢复到730mAh/g.该材料也表现出优异的循环性能,在5和10A/g电流密度下依次循环100圈,容量保持率几乎100%.     

Densification behavior of mechanically milled Cu–8 at% Cr alloy and its mechanical and electrical properties

Synthesis and consolidation behavior of Cu–8 at%Cr alloy powders made by mechanical alloying with elemental Cu and Cr powders,and subsequently,compressive and electrical properties of the consolidated alloys were studied.Solid solubility of Cr in Cu during milling,and subsequent phase transformations during sintering and heat treatment of sintered components were analyzed using X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The milled powders were compacted applying three different pressures(200 MPa,400 MPa and 600 MPa)and sintered in H2atmosphere at 900 1C for 30 min and at 1000 1C for 1 h and 2 h.The maximum densification(92.8%)was achieved for the sample compacted at 600 MPa and sintered for 1000 1C for 2 h.Hardness and densification behavior further increased for the compacts sintered at 900 1C for 30 min after rolling and annealing process.TEM investigation of the sintered compacts revealed the bimodal distribution of Cu grains with nano-sized Cr and Cr2O3precipitation along the grain boundary as well as in grain interior.Pinning of grain boundaries by the precipitates stabilized the fine grain structure in bimodal distribution.     

Growth, structural, optical, thermal and dielectric properties of a novel semi-organic nonline ar optical crystal: Dichloro-diglycine zinc II

Dichloro-diglycine zinc II(DCDGZ II),a semi-organic nonlinear optical material has been synthesized and single crystals were grown from the aqueous solution up to dimensions 20×10×3 mm3.The title compound,DCDGZ II(C4H10Cl2N2O4Zn H2O) crystallizes into monoclinic structure with the space group of C2/c.The unit-cell parameters were found to be a=14.4191(7),b=6.9180(2),c=12.9452(6) and Z=4.In the crystal structure,DCDGZ II layer is building up alternatingly with layers of water in which the zinc ions lie on a twofold axis.Theoretical calculations for polarizability,which are useful for device fabrication were made using Clausius–Mosotti equation and Penn analysis and the results were compared.Fourier transform infrared(FTIR) spectroscopic studies were performed for the identification of the different functional groups presented in the compound.The UV–vis–NIR absorption spectrum reveals that the lower UV cut-off wavelength is 240 nm.The optical band gap of the crystal was estimated as 2.2 eV.The surface morphology,thermal behaviour,dielectric properties have been studied using SEM,TG/DTA and LCR HITESTER analyzer.The nonlinear optical property of the crystal was also confirmed using Kurtz powder technique.     

纳米材料与低压膜技术的耦合及其在饮用水处理中的应用

低压膜过滤可以在50~100kPa的工作压力下,高效去除水中的颗粒污染物,也可与其他工艺结合,实现饮用水的深度处理,因此在我国正得到日益广泛的应用.近年来,纳米材料技术的进步,为膜法水处理技术的提高提供了新的可能.本文结合作者的部分研究工作,对低压膜过滤的基本原理、纳米复合膜的制备、纳米水处理膜处理工艺的组合,及相关技术在农村饮用水处理和咸水脱盐的应用等方面,进行了简单综述,以为相关领域的学科交叉提供一些可能思路,最终为改善我国的饮用水安全状况提供技术支持.     

被动式太阳能结合相变墙在苏北自然通风环境下的应用研究

通过建立实体的模型房间,选择寒冷的冬季和炎热的夏季两种环境,对被动式太阳能建筑结合相变墙体的综合应用状态进行了模拟研究,获得了太阳能集热墙、相变墙体等结构的表面温度及室内温度参数,利用动态热网络分析法,建立综合考虑建筑内部舒适度的4种运行工况,通过对比分析的方法,验证了由被动式太阳能建筑结合相变墙体的实验房具有冬暖夏凉的功能。在炎热的夏季,相变墙发挥了蓄冷作用,同时太阳能集热墙的被动通风,使得实验房内白天温度较普通房有所下降;在寒冷的冬季,白天太阳能集热墙的吸热与相变材料的蓄热,使得实验房内夜晚温度较普通房有所上升,从而实现实验房冬暖夏凉的功能。     

提钒转炉用MgO--Fe--C砖性能研究

为延长MgO-C砖在提钒转炉上的使用寿命,本研究开发了一种新型MgO-Fe-C砖,通过与传统的MgO-C砖进行对比研究,考察这种新型耐火材料的使用性能。研究结果表明：在1400℃的使用温度下,导致提钒转炉用MgO- C砖使用寿命短的原因是脱碳层的烧结性差,抗冲刷性不理想;而对于本研究所开发的MgO-Fe-C砖,铁粉在氧化层氧化及使用条件下原位形成MgO-FeOss,有效地改善脱碳层的烧结性能,并形成致密且高结合强度的脱碳层,显著地提高了耐火材料的抗熔渣侵蚀性和抗氧化性,有利于耐火材料寿命的提高,因此MgO-Fe-C砖是具有良好应用前景的提钒转炉用MgO-C砖的替代品。     

泛形裂面构造及其复杂度

基于真实材料物理性质的非均匀特征,提出了一个简单的统计泛形裂纹扩展模型,用以描述脆性材料中泛形裂纹（或断裂面）构形,并采用计盒维数方法确定其复杂度.其中,假设裂纹沿最小能量耗散（依次按最小强度、最短路径、最小偏折角判定）方向扩展,且材料性质服从Weibull分布.计算得到的泛形裂纹构形的复杂度结果与实验结果吻合较好.进一步分析表明,泛形裂纹构形的复杂度可由材料性质的Weibull分布参数确定,而与泛形裂纹构形的随机性或涨落无关.