电子束辐照对氧化锌纳米线I-V特性的影响

在扫描电镜中,采用纳米微操纵仪构成一个2探针电流-电压（I-V）测试装置。测试了单根ZnO纳米线接触钨电极构成的金属-半导体-金属（M-S-M）结的I-V特征曲线。ZnO纳米线的I-V曲线呈现出较弱的肖特基特性。研究了电子束辐照对ZnO纳米线的I-V曲线的影响。30 keV电子束辐照使ZnO纳米线的总电阻减小。计算得到ZnO纳米线的电导率σ=0.24S/cm,载流子浓度n=1.64×10^16cm^-3。为了对比,还测试了单根碳纤维接触钨电极的I-V特征曲线。在30 keV电子束辐照下,碳纤维的总电阻保持不变,电导率σ=22 S/cm。     

基于单根氧化锌纳米线的场效应管的光电特性研究

本文介绍了一种基于单根氧化锌纳米线场效应管的制备方法,用XRD和SEM分析了样品的结构和形貌,测试了它的输出特性曲线和转移特性曲线.当Vds=2 V时,测得场效应管的开启电压Vgt=-16.2 V;计算得到低频跨导gm=46.6nS.在Vgs=0 V时,测得一维ZnO纳米线的载流子浓度n=1.15×108 cm-1,电子迁移率μe=14.4 cm2/Vs,电导率σ=0.26 Ω-1 cm-1.该场效应管的上限截止频率fH=1585 Hz,漏源极间电容C=25.4 pF.本文还对基于单根氧化锌纳米线的场效应管的光电灵敏度和光电时间响应进行了测试分析.     

ZnO纳米线气敏元件对单一气体浓度的判定研究

以不同金属掺杂的ZnO纳米线为气敏材料,在350℃下对不同浓度的H2气体进行了气敏性能测试.结果表明,掺杂Ag的ZnO纳米线在H2浓度为2.52×10(-3)时具有较高的气体灵敏度28.549.同时,利用Origin软件对测得的气敏性能曲线进行线性拟合,对未知的H2浓度进行了有效判定.还对金属掺杂提高ZnO纳米线气敏性...     

射频磁控溅射纳米二氧化钒薄膜的电致相变特性

采用射频磁控溅射方法和热处理工艺制备了二氧化钒（VO2）薄膜,并制作了金属钨／VO2／金属钨三明治结构,通过改变金属钨／VO2／金属钨三明治结构中VO2薄膜与金属钨电极的接触面积,研究了VO2薄膜的电致相变特性．采用x射线衍射仪（XRD）、扫描电子显微镜（SEM）、四探针和半导体参数测试仪对VO2薄膜的结晶取向、表面形貌、方块电阻和,I-V特性进行了测试．实验结果表明,所制备的VO2薄膜为具有热致相变特性的单一组分VO2纳米薄膜,在热激励下,薄膜的方块电阻相变幅度达到2个数量级;在电压的激励下,VO2薄膜与金属钨的接触面积为12μm×12um时,电流发生跳变的阁值电压为9．4V,随着接触面积的减小,闽值电压也逐渐降低．     

ZnO白漆的质子辐照损伤与光学性能退化机理

为进一步阐明ZnO白漆的辐照损伤与光学性能退化机理,在模拟的空间环境下对S781白漆进行了150keV质子辐照实验。质子辐照后,在原位条件下测试了光谱反射系数和太阳吸收比的退化规律,并利用模拟仿真和光致荧光光谱研究了ZnO白漆与质子间的微观交互作用和辐照诱发缺陷。结果表明,质子辐照下ZnO颜料发生电离生成-1价锌空位,是S781白漆出现b带吸收和光学性能退化的主要原因。此外,本工作支持了ZnO绿带荧光源于锌空位的第一原理计算结果。     

基于p+-Si与n-ZnO纳米线的p-n异质结的制备及其性质研究

利用CVD蒸汽俘获法，在p^＋硅片上制备了垂直生长的n型ZnO纳米线阵列，用XRD和SEM分析了样品的结构与形貌。测试发现样品的I-V曲线符合典型的p-n异质结特性，正向开启电压为0．5V，反向饱和电流为0．02mA。计算了异质结的理想因子η，发现当异质结两端偏压在0V-0．3V的低压区域，理想因子为1．85，而在0．3v-0．8v的高偏压区域，理想因子为8．36。解释了理想因子偏高的原因是由于金属一半导体接触以及ZnO纳米线与p^＋-si界而存在缺陷。     

纳米线阵列的电化学优化光吸收增强研究

通过在自生长的半导体Cu2S纳米线阵列表面进一步应用电化学表面沉积处理,在纳米线表面形成尺寸更小的Cu2S纳米颗粒结构,实现了在不减小纳米线直径或增加纳米线长度的情况下,有效提高了纳米线阵列光吸收性能。利用I-V循环扫描曲线研究了以Cu2S纳米线阵列为工作电极的Cu2S沉积电位,利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见-近红外分光光度计,对纳米阵列的相结构、微观表面形貌、晶体结构及光吸收能力进行了表征和分析。研究表明:沉积于单斜晶系Cu2S纳米线阵列上的纳米颗粒为斜方晶系Cu2S,沉积后纳米线表面结构改变,粗糙度明显增加,起到了减少纳米线的光反射、优化原纳米线阵列光吸收综合能力的作用。     

ZnO纳米线阵列湿度传感器研究

采用水热法在Au/Ni叉指电极上原位生长出整齐的ZnO纳米线阵列。纳米线的平均直径和长度分别为50 nm和5μm,且沿[0001]方向高度择优生长。测试了基于纳米线阵列的湿敏器件对不同湿度电容和电阻响应,并分析了它的工作机制。实验结果表明,这些器件具有相对较大的灵敏度和较短的响应和恢复时间,从而说明ZnO纳米线阵列在湿敏领域有很好的应用前景。     

中温固体氧化物燃料电池阴极材料Ln_(0.6)Sr_(0.4)Fe_(1-χ)Co_χO_(3-δ)的合成和性能表征

采用固相反应法合成了中温固体氧化物燃料电池阴极材料Ln0.6Sr0.4Fe1-χCoχO3-σ（Ln=La,Pr;Nd,Sm和Gd）粉体.对其进行结晶学表征,分析氧含量和失重与温度的关系,并研究了其电导率随温度的变化规律及其与Ce0.8Gd0.2O1.9（CGO）电解质的化学相容性.实验表明,600～800℃;所有样品的电导率均高于100S/cm,其中Nd0.6Sr0.4Co0.8Fe0.2O3-σ的电导率高达600S/cm,并且与CGO电解质都具有良好的化学相容性.     

碳纤维水泥石压敏传感器电极的实验研究

电极的设计是制作碳纤维水泥石压敏传感器的重要环节之一。本文首次提出了埋入式网状电极的概念,同时综合分析了网状电极的特点。本文的研究表明埋入式铜质网状电极具有相容性和耐久性好、极化作用和接触电阻小等优点,是碳纤维水泥石压敏传感器的理想电极;在电阻测试中,四极法较两极法具有更高的准确性。此外,本文还研究了电极的结构参数对四极法测试结果准确性的影响。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。