La0.67 Sr0.33 MnO3外延薄膜的电脉冲诱发可逆变阻效应

采用脉冲激光沉积技术在SrTiO3,(001)单晶衬底上制备出钙钛矿结构La0.67 Sr0.33 MnO3,(LSMO)外延薄膜,通过X射线衍射仪和原子力显微镜表征其晶体取向与表面形貌,并对Ag-LSMO结构的室温电脉冲诱发可逆变阻效应进行研究.结果表明,在±4V、50ns对称脉冲作用下,LSMO膜层电阻发生高低转变,且变阻范围随脉冲幅值电压、脉冲宽度、脉冲数日等参数的变化而变化.该效应表现出良好的疲劳特性与非挥发存储特性,有望应用于新型不挥发存储器、传感器、可变电阻等电子元器件的研制.     

La-Ca-Mn-O巨磁电阻薄膜的电阻变化

研究了类钙铁矿结构La0.67Ca033MnOx巨磁电阻薄膜(生长在LaAlO3衬底)的电阻变化,观察到负巨磁电阻效应,讨论了优化制备工艺提高巨磁电阻效应和最大电阻温度,其效应可用于设计新电磁器件。同时讨论了巨磁电阻效应的机理,给出合理解释。     

La—Ca—Mn—O巨磁电阻薄膜的电阻变化

研究了类钙钛矿结构Ｌａ０．６７Ｃａ０．３３ＭｎＯｘ巨磁电阻薄膜（生长在ＬａＡｌＯ３衬底）的电阻变化，观察到负巨磁电阻效应，讨论了优化制备工艺提高巨磁电阻效应和最大电阻温度，其效应可用于设计新电磁器件。同时讨论了巨磁电阻效应的机理，给出合理解释。     

Ag／La0.67Sr0.33MnO3/Pt异质结构的电阻开关特性

采用脉冲激光沉积技术在Pt／Ti／SiO2／Si（100）衬底上制备出多晶La0.67Sr0.33MnO3（LSMO）薄膜,对其电脉冲致非挥发可逆电阻开关特性进行研究．结果表明,Ag/LSMO／Pt结构具有明显的室温电脉冲诱发电阻开关特性,且在宽电压脉冲作用下表现出较低的开关电压和较快的变阻饱和速度．由此可见,总脉冲能量或电荷（电流作用）为该结构的电阻开关效应提供驱动力．对Ag／LsMO／Pt结构进行了耐久性测试,表明该结构具有良好的疲劳特性与保持特性,可应用于新型不挥发存储器、传感器及可变电阻等电子元器件的研制     

磁性多层膜的正巨磁电阻特性

采用离子束溅射方法制备了正巨磁电阻多层膜，在制备过程中采用外加磁场和退火处理。在室温条件下多层膜的巨磁电阻效应达到200％～300％，并用磁矩取向的双电流导电模型对正磁电阻的机理进行了解释。     

NiFe/Ag多层膜在低场下的巨磁电阻行为

用磁控溅射法制备了NiFe/Ag多层膜 ,并从实用角度对NiFe/Ag多层膜的低场巨磁电阻效应作了研究。分析了该膜系列产生低场巨磁电阻效应的机理 ,并进行了实验研究 ,最终获得在低场 (小于 79 6× 2 5 0A/m)常温下有高达 5 0 %巨磁电阻效应的材料     

碳纳米管压阻效应及其应用研究

利用了三点弯曲法研究了碳纳米管膜压阻效应.研究中所用的碳纳米管是用化学气相沉积法合成的.实验结果表明,碘掺杂和未掺杂的碳纳米管膜的压阻因子在500微形变和室温下分别为350和65,超过了单晶硅和多晶硅的压阻因子.同时还发现化学处理还能进一步增强碳纳米管膜的压阻效应.碘掺杂碳纳米管膜的压阻效应也许是由于在形变时带隙变化所致,而未掺杂碳纳米管压阻效应主要是由管之间接触电阻变化引起的.碳纳米管压阻效应可用于旋转速度的测量.     

Cu层和Mo层对NiFe多层膜巨磁电阻（GMR）的影响

采用磁控溅射方法制备了ＮｉＦｅ／Ｃｕ和ＮｉＦｅ／Ｍｏ两个系列的多层膜，进行了结构，磁性和磁电阻测量，并对部分ＮｉＦｅ／Ｃｕ多层膜样品作了电镜分析，对于ＮｉＦｅ／Ｃｕ多层膜，在室温下的测量到巨磁电阻随Ｃｕ层厚度振荡的第一，二三峰。在ＮｉＦｅ／Ｍｏ多层膜样品中未发现巨磁电阻效应，讨论了非磁性 多层膜的磁性，界面结构和巨磁电阻效应。     

Fe3O4-PDMS纳米复合材料磁电阻特性及变化模型的研究

主要研究了复合材料磁电阻特性,提出了复合材料的制备方法,并测量了材料形貌、磁化特性、磁电阻随磁场的变化特性。结果表明,复合材料在环境磁场中能够产生磁电阻效应,其磁电阻特性受材料中分散的纳米颗粒的磁化特性所影响,并且复合材料磁电阻随着材料中纳米颗粒的分散浓度的增大而增大。根据磁场环境下复合材料中纳米颗粒之间沿磁场方向的相互作用以及聚合物材料的粘弹性,重点分析了该复合材料的磁电阻变化机理并提出了复合材料的磁电阻变化模型。随后,利用纳米颗粒的磁化数据以及PDMS的动力学参数进行了复合材料磁电阻变化特性的数值仿真,并将仿真数据与实测数据进行对比,对比结果显示该模型能够准确描述复合材料的磁电阻变化特性。     

氩等离子体处理对ZnO薄膜阻变效应的影响

本文研究了氩等离子体处理对ZnO薄膜阻变效应的影响,发现等离子体处理可以使薄膜表面平整,并且增加薄膜中的缺陷浓度。以等离子体处理后的ZnO薄膜作为介质层,在Pt/ZnO/Pt三明治结构中观察到无电形成过程的阻变效应。本文研究表明,氩等离子体处理是消除氧化物阻变效应电形成过程的有效手段。     

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.     

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.     

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.     

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)。