Interlaboratory Comparison on High-Temperature Superconductor Critical-Current Measurements

An extensive interlaboratory comparison was conducted on high temperature superconductor (HTS) critical-current measurements. This study was part of an international cooperative effort through the Versailles Project on Advanced Materials and Standards (VAMAS). The study involved six U.S. laboratories that are recognized leaders in the field of HTS. This paper includes the complete results from this comparison of critical-current measurements on Ag-sheathed Bi₂Sr₂Ca₂Cu₃O_10–x (2223) tapes. The effects of sample characteristics, specimen mounting, measurement technique, and specimen damage were studied. The future development of a standard HTS measurement method is also discussed. Most of the evolution of this emerging technology has occurred in improvement of the performance of the conductors. The successful completion of this interlaboratory comparison is an important milestone in the evolution of HTS technology and marks a level of maturity that the technology has reached.     

焊接滤光片可见光透射比实验室间比对及其结果评价

开展焊接滤光片可见光透射比实验室间比对,采用稳健统计法对焊接滤光片可见光透射比不同实验装置的检测能力进行评价,增加实验室对所使用的实验装置检测能力的了解,并最终提高实验室检测能力。     

Development of a Thin Film Magnetic Moment Reference Material

In this paper we present the development of a magnetic moment reference material for low moment magnetic samples. We first conducted an inter-laboratory comparison to determine the most useful sample dimensions and magnetic properties for common instruments such as vibrating sample magnetometers (VSM), SQUIDs, and alternating gradient field magnetometers. The samples were fabricated and then measured using a vibrating sample magnetometer. Their magnetic moments were calibrated by tracing back to the NIST YIG sphere, SRM 2853.     

Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors

We have investigated magnetic hysteresis in transport critical-current (I_c) measurements of Ag-matrix (Bi,Pb)₂Sr₂Ca₂Cu₃O_10–x (Bi-2223) and AgMg-matrix Bi₂Sr₂CaCu₂O_8+x (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current of high temperature superconductors is a very important consideration for every measurement procedure that involves more than one sweep of magnetic field, changes in field angle, or changes in temperature at a given field. The existence of this hysteresis is well known; however, the implications for a measurement standard or interlaboratory comparisons are often ignored and the measurements are often made in the most expedient way. A key finding is that I_c at a given angle, determined by sweeping the angles in a given magnetic field, can be 17 % different from the I_c determined after the angle was fixed in zero field and the magnet then ramped to the given field. Which value is correct is addressed in the context that the proper sequence of measurement conditions reflects the application conditions. The hysteresis in angle-sweep and temperature-sweep data is related to the hysteresis observed when the field is swept up and down at constant angle and temperature. The necessity of heating a specimen to near its transition temperature to reset it to an initial state between measurements at different angles and temperatures is discussed.     

纳米高频软磁薄膜材料研究进展

由于高频软磁薄膜材料具有巨大的应用前景因此获得了人们广泛的关注。对纳米合金软磁薄膜、纳米软磁颗粒膜、多层膜以及图形化薄膜进行了分类综述,分别介绍了各类薄膜的制备方法、化学成分、微观结构特点和高频物理性能,并对影响其性能的主要因素进行了讨论。由于纳米高频软磁薄膜材料相对于传统磁性材料具有显著优势,所以纳米合金软磁薄膜有望取代铁氧体作为制作高频磁性器件的主要应用材料。由于纳米软磁颗粒膜、多层膜以及新兴的图形化薄膜具有材料结构设计和物性剪裁的自由度,因此将是今后的重点研究方向。     

聚苯胺薄膜的制备及其C—V特性研究

报导了采用PECVD技术制备聚苯胺薄膜及沉积条件对薄膜沉积速率的影响,红外吸收光谱和电容－电压法表征了薄膜的组成及介电特性。     

软磁性薄膜微波磁特性的研究进展

概述了软磁性单层膜、多层膜、颗粒膜的微波磁特性研究进展,对这些薄膜的基本磁性和微波磁性进行了总结和讨论,得出软磁纳米晶薄膜可望成为应用于微波领域的主体候选材料,指出了Co(Fe)基软磁性薄膜微波特性的研究方向.     

Statistics and Measurements

For more than 50 years, the Statistical Engineering Division (SED) has been instrumental in the success of a broad spectrum of metrology projects at NBS/NIST. This paper highlights fundamental contributions of NBS/NIST statisticians to statistics and to measurement science and technology. Published methods developed by SED staff, especially during the early years, endure as cornerstones of statistics not only in metrology and standards applications, but as data-analytic resources used across all disciplines. The history of statistics at NBS/NIST began with the formation of what is now the SED. Examples from the first five decades of the SED illustrate the critical role of the division in the successful resolution of a few of the highly visible, and sometimes controversial, statistical studies of national importance. A review of the history of major early publications of the division on statistical methods, design of experiments, and error analysis and uncertainty is followed by a survey of several thematic areas. The accompanying examples illustrate the importance of SED in the history of statistics, measurements and standards: calibration and measurement assurance, interlaboratory tests, development of measurement methods, Standard Reference Materials, statistical computing, and dissemination of measurement technology. A brief look forward sketches the expanding opportunity and demand for SED statisticians created by current trends in research and development at NIST.     

Inorganic Thin Film Deposition and Application on Organic Polymer Substrates

This review details the emerging area of inorganic thin film coatings on polymer substrates, from examples of applications through to the fabrication processes and the underlying growth mechanism(s). Of particular focus is the use of physical vapor deposition to deposit thin metal and/or metal oxide films onto polymeric materials. This primary focus highlights an area of research, that is, gaining in popularity, as researchers attempt to provide insight into the adaption of a well‐established manufacturing process to be compatible with the ever expanding range of polymer substrates. The motivation for doing so comes from the evolution of existing industry (i.e., the semi‐conductor sector) to fabricate new devices (i.e., flexible electronics). In addition, the research challenges faced in achieving evaporated and sputtered thin film coatings on polymeric substrates, such as mechanical and thermal considerations will be discussed.

     

Randomly Distributed Vacancies Influence on Magnetic Properties of the Bilayer Thin Film

In this paper we are investigating the magnetic behavior of the double-layer thin film in the extended Heisenberg model, with long-range dipolar interaction, taking into account the influence of the randomly distributed vacancies on the magnetic properties of the system. We are studying the physical quantities of interest (magnetization, magnetic susceptibility and specific heat) via Monte Carlo technique, by applying the standard Metropolis algorithm. In this context, we investigate the critical temperature variation for different vacancies concentration levels, taking into account the uniform and the superficial distribution of the defects, respectively.      

钡铁氧体垂直磁化膜磁各向异性研究

钡铁氧体垂直磁化膜可用作高密度磁记录介质。本文研究用低温ＲＦ磁控溅射法制备非晶薄膜，经晶化处理所得到的垂直磁化膜的饱和磁化强度Ｍｓ、矫顽力Ｈｃ及垂直磁各向异性常数Ｋｕｌ、Ｋｕ２与退火温度Ｔ的关系，并对所呈现出的变化规律作了简单解释。介绍了依据转矩曲线的形状来判断薄膜垂直性优劣的方法，从转矩曲线出发，探讨了影响薄膜磁各向异性的因素。     

大区国家计量中心电能标准量值比对

2003年9月至2004年8月进行了大区国家计量中心电能标准量值比对,比对程序参照了国际关键比对的方法,比对结果的分析表明,所有参加机构所报告的测量值与国家基准之差均在比对数据的不确定度范围内,故所有参加比对机构所声明的不确定度是合理的.     

Thermal Diffusivity Measurements of Thermographite

This paper presents results of measurements of a graphite proposed to serve as a thermophysical property reference or standard reference material. The reported measurements contribute to a program launched in 1999 by Anter Corp. with the objective to provide a replacement for the NIST thermal property reference material RM AXM-5Q graphite whose supplies were being exhausted. Measurements of the thermal diffusivity performed on five specimens taken from different positions within a large graphite block between room temperature and 1300 K were in good mutual agreement. Measurements of NIST reference AXM-5Q graphite sample supplied to minimize effects of different contributors to a common base were also in good agreement, both with the NBS reference function established by Hust in 1984 and contributions to the NBS project from the Vinca Institute of Nuclear Sciences carried out in 1979. The influence of different data reduction techniques on the measured thermal diffusivity values is illustrated and discussed.     

薄膜太阳能电池

薄膜太阳能电池作为一种新的能源材料正在得到迅速的发展和进步,主要介绍了非晶硅、多晶硅薄膜太阳能电池以及CIGS薄膜太阳能电池,通过比较这几种薄膜太阳能电池各自的特点阐述了各种薄膜太阳能电池的发展状况.     

末端形状对磁纳米薄膜自旋波模式特性的影响

基于微磁学模拟方法研究了磁纳米膜末端形状对自旋波模式特性的影响。获得了多种不同的局域化、量子化自旋波模式特性,以及末端形状对自旋波模式特性的调制规律。通过裁剪纳米膜的末端形状可有效调控边缘模式自旋波特性,存在一临界裁剪参数h0。当裁剪度hh0时,随着h的增大,边缘模式频率快速增加,局域于磁薄膜两末端的磁振荡区域向中央扩展。当h≥h0时,局域于磁薄膜两末端磁振荡在磁体中央合并为一致振荡模式自旋波,边缘模式被抑制。薄膜末端边缘形状对别的自旋波模式特性影响较小。最后,基于近似色散关系理论模型对研究结果进行了解释。