Fe-Ni合金薄膜组成表面分析测量国际

利用X射线光电子能谱技术,建立了Fe-Ni合金薄膜组成表面分析准确定量方法,中国计量科学研究院参加了国际关键比对CCQM-K67。根据最近公布的关键比对结果,中国计量科学研究院测量的Fe原子分数结果为51.48%,与参加的各国国家计量研究院的结果（50.02%）达到了等效一致。     

~(125)I放射性溶液活度测量国际比对

2004年6-8月,中国计量科学研究院电离辐射处参加了国际计量局(B IPM)组织的125I放射性溶液活度测量国际关键比对。我们采用KX射线和γ射线的探测效率符合相加原理,选用4π井形NaI晶体测量装置对125I的活度进行绝对测量。测量结果与平均值相差1.3%.     

中国参加温度关键比对结果分析

本文介绍了国际计量委员会(CIPM)组织国际关键比对的背景和已经开展的温度比对项目。对中国计量科学研究院参加的温度比对项目进行了系统介绍和结果分析。     

中国参加温度关键比对结果分析

本文介绍了国际计量委员会(CIPM)组织国际关键比对的背景和已经开展的温度比对项目。对中国计量科学研究院参加的温度比对项目进行了系统介绍和结果分析。     

正多面棱体国际关键比对

简要地介绍了国际计量局(BIPM)组织国际关键比对与"国家计量标准和国家计量院签发的校准证书的相互承认"协议(iRA)的相互关系,给出了中国计量科学研究院参加BIPM组织的正多面棱体CCL-KS关键比对的测量方法、不确定度参量及比对结果.     

国际角度关键量值-角度块比对的方法及结果

介绍了中国计量科学研究院在2000年度CIPM组织的CCL-KC3国际角度关键量值比对项目中的角度块比对中所采取的测量方法、测量结果及不确定度分析,并提供了CIPM发布的各参比实验室的角度块比对数据,供国内角度计量领域的同行进行参考.我国的4个角度块的比对数据比较接近平均值,同时加权值En均小于1,说明我国提供的角度块的测量不确定度结果是合理的.     

633 nm激光波长基准/副基准比对

对中国计量科学研究院、中国计量测试技术研究院和长城计量测试技术研究所的633 nm127I2饱和吸收稳定激光波长基准、副基准进行了比对,这是首次进行的国内长度基准的比对.比对实验的内容包括频率稳定度测量、频差测量和相关的位移参数测量等.给出了以国际计量局BIPM C1为参考的比对结果.     

低能X射线空气比释动能国际关键比对

为促进我国在低能X射线空气比释动能计量领域内的量值统一并达到国际等效,中国计量科学研究院(NIM)于2018年采用平板自由空气基准电离室复现低能X射线空气比释动能,并通过传递电离室Radcal-RC6M在国际计量局(BIPM)低能X射线辐射场中开展了间接比对,其比对结果在合成标准不确定度为0.37%范围内与国际计量局等效一致,该比对结果已纳入国际计量局的关键比对数据库(KCDB)。     

缩宫素纯度测量的国际比对及国际互认

为实现缩宫素测量结果的溯源性、准确性、一致性和可比性，中国计量科学研究院与国际计量局联合主导了缩宫素纯度测量的国际比对，即CCQM-K115.b/P55.2.b。该比对于2016年开始，2020年完成，历时4年。国际计量局、中国、巴西、英国、日本、土耳其、墨西哥、马来西亚、加拿大等9个国家/国际组织的计量机构参加了该比对，采用质量平衡法、水解法、定量核磁法、元素分析法等4种方法完成了缩宫素比对样品的测量。经国际计量委员会蛋白质分析工作组讨论，参考值为（787.2±12.9）mg/g。在关键比对中，我国报告的质量平衡法结果为（796.5±6.5）mg/g，取得等效，且不确定度最小。基于该国际比对结果，我国申报了通用校准与测量能力，覆盖含单个二硫键、分子量小于5000道尔顿的多肽纯度测量，并于2021年发布在国际计量局的关键比对数据库，表明该能力取得国际互认。     

细胞定量国际比对CCQM-P102及流式细胞技术的不确定度评定

对中国计量科学研究院应邀参加2010年CCQM-P102“具有特定表型的细胞定量测量比对”的测量过程、数据分析及不确定度评定进行了阐述。比对结果表明,中国计量科学研究院CD4+细胞计数测量结果与各参加国达到等效一致,成绩良好;其测量细胞平均CD4抗原值的细胞荧光强度值在经过对数转换及线性回归后,计算结果在国际比对不确定度范围内,并作为该比对提交测量不确定度的3个国家之一。对流式细胞术的测量不确定度评定进行了探讨。     

NIM新一代二端对电容电桥装置

基于一种交流电桥自动辅助平衡方法,中国计量科学研究院(NIM)研制了新一代二端对电容电桥装置。电桥采用固定比率的感应耦合比率臂电桥,通过复用比率,用单一电桥即实现了计算电容过渡和电容10:1传递;采用一种改进的靴带法实现电桥感应比率臂比率的精确校验。该装置用于电容单位的量值复现和标准电容器的高准度量值传递。利用新一代二端对电容电桥装置,可从计算电容装置复现1 pF电容值,并实现电容 1~100 pF的十进制量值传递,电容量值传递相对标准不确定度可达5×10^-9(1592 Hz)。采用该电桥参加了10 pF和100 pF电容国际关键比对(CCEM.K4-2017),中国比对成绩优异,数据均非常接近关键比对参考值(KCRV),其中100 pF的结果最接近KCRV,与KCRV取得了很好的一致性,从而获得国际互认。     

Grinding of Single-Crystal Silicon Using a Microvibration Device

This paper presents experimental results of grinding of single-crystal silicon using a microvibration device and a diamond grindingwheel. Samples were cut from (100) silicon. The grinding direction was parallel to the [110] direction of (100) silicon. These samples were ground under the same grinding conditions but with different vibration directions, frequencies, and/or amplitudes. The surface roughness and the surface texture of all samples were analyzed for comparison. The R_a, R_q, and R_t values and the microphotographs of the ground silicon surfaces showed the dependency of surface finish on the grinding with vibrations. Samples ground with vibrations had better surface finish compared with the silicon surfaces ground without vibrations. Out of the 12 experiments, the best surface finish was achieved when (100) silicon was ground with horizontal vibrations at a 70-Hz frequency and 6-μm amplitude perpendicular to the grinding direction.     

Silicon spintronics

Worldwide efforts are underway to integrate semiconductors and magnetic materials, aiming to create a revolutionary and energy-efficient information technology in which digital data are encoded in the spin of electrons. Implementing spin functionality in silicon, the mainstream semiconductor, is vital to establish a spin-based electronics with potential to change information technology beyond imagination. Can silicon spintronics live up to the expectation? Remarkable advances in the creation and control of spin polarization in silicon suggest so. Here, I review the key developments and achievements, and describe the building blocks of silicon spintronics. Unexpected and puzzling results are discussed, and open issues and challenges identified. More surprises lie ahead as silicon spintronics comes of age.     

An Analysis of Germanium–Silicon/Silicon Strained Superlattice Structure Using Convergent Beam Electron Diffraction

Strained superlattices (SSLs) are typically found inside the p‐n junction area of semiconductor devices and consist of very thin alternating layers of different material. There exists a small lattice mismatch between these materials which results in localised strain, as in the case of germanium‐silicon/silicon SSLs. Strain measurements using a convergent beam electron diffraction (CBED) technique inside a transmission electron microscope (TEM) have indicated that the strain measured normal to these germanium–silicon/silicon SSLs varies almost sinusoidally, in spite of theoretical predictions which indicate a much sharper change in strain between these layers. A theoretical formulation involving an elasticity solution has been developed to predict the strain inside these SSL structures. The comparison of theoretical and experimental results clearly quantifies the effect of beam size on the spatial resolution of CBED measurements. Given that beam size is critically dependent on the spot size of the beam, the convergence angle, the specimen thickness and the position of the focused plane, these parameters are all clearly accounted for in the theoretical predictions.     

高硅铁尾矿合成SiC粉体技术研究

以高硅铁尾矿为主要原料,利用碳热还原法合成了SiC粉体。分析了合成过程的反应机理,探讨了配碳量和合成温度对合成过程的影响。结果表明,最终产物中β-SiC为主晶相,FexSiy为次晶相;影响合成SiC粉体最主要的因素是配碳量,其次是反应温度;在保证配碳过量的情况下,保温时间和氩气流量对合成产物的影响不是很明显;产物晶粒存在多种几何形状,其中SiC晶粒多以片状、柱状、球状形式存在,并且晶粒表面比较光滑,晶粒的尺寸分布不均匀。合成SiC的最佳工艺参数为:n(C):n(SiO2)=5,合成温度1500℃,恒温时间8h,氩气流量0.6L/min。     

Silicon detectors in electromagnetic and hadronic calorimetry

A review of investigations performed by SICAPO collaboration at CERN and Si/W and Si/U sandwich calorimeters employing silicon detectors as active medium is presented. Experimental results, such as the response of sensed energy versus incoming electron energy and depleted layer width, of the longitudinal and lateral development of electromagnetic showers and of the energy resolution, are described. Mosaic modules of silicon detectors, which enable the construction of silicon sampling hadronic calorimeters, are also given. A comparison of results from SICAPO, Hamburg (Si/Pb) and from Tokyo (Si/Pb and Si/W) calorimeters is shown.     

Nanopores in Macroporous Silicon

Macroporous silicon is studied by IR absorption spectroscopy, x-ray diffraction, and the electron–positron annihilation method in comparison with single-crystal Si (substrate), polycrystalline Si (powder), anda-SiO₂ (silica glass). According to IR absorption data, as-prepared macroporous silicon contains a significant amount of oxidized material. Annihilation spectra of macroporous silicon attest to the presence of a system of nanopores, in which positronium atoms are likely to localize. Diffraction patterns reveal considerable amounts of silicon particles oriented at random. Both the polycrystalline phase and nanopores reside on the surface of macropores.     

Highly Porous Silicon Membranes Fabricated from Silicon Nitride/Silicon Stacks

Nanopore formation in silicon films has previously been demonstrated using rapid thermal crystallization of ultrathin (15 nm) amorphous Si films sandwiched between nm‐thick SiO₂ layers. In this work, the silicon dioxide barrier layers are replaced with silicon nitride, resulting in nanoporous silicon films with unprecedented pore density and novel morphology. Four different thin film stack systems including silicon nitride/silicon/silicon nitride (NSN), silicon dioxide/silicon/silicon nitride (OSN), silicon nitride/silicon/silicon dioxide (NSO), and silicon dioxide/silicon/silicon dioxide (OSO) are tested under different annealing temperatures. Generally the pore size, pore density, and porosity positively correlate with the annealing temperature for all four systems. The NSN system yields substantially higher porosity and pore density than the OSO system, with the OSN and NSO stack characteristics fallings between these extremes. The higher porosity of the Si membrane in the NSN stack is primarily due to the pore formation enhancement in the Si film. It is hypothesized that this could result from the interfacial energy difference between the silicon/silicon nitride and silicon/silicon dioxide, which influences the Si crystallization process.