InP中的孪晶和晶界的同步辐射研究

实验观测到X射线反向曲线具有双晶特征。研究表明缺陷聚集在孪晶晶界。应力在晶界边缘处得到释放。应力的释放导致享晶和其它缺陷的形成。由于缺陷的形成在缺陷的附近产生无位错无应力或低位错小应力区。因此我们提出一种孪晶模型来解释实验结果。应力（主要是热应力），化学配比的偏离和杂质的非均匀分布是液封直接（LEC）InP单晶生长过程中产生孪晶的主要因素。研究了液封直拉（LEC）InP(111）面上的孪晶。本中讨论了上面提到的孪晶模型的实验证据和如何得到无孪晶液封直接（LEC）InP单晶。     

硅藻土,硬铝,不锈钢,金属铜和镍中杂质含量的全分析

为提供NDA标准样品用的基体材料,容器材料和镀层材料中杂质元素含量的有关数据,并建立杂质元素含量的全分析方法,采用火花源质谱法分析了硅藻土,硬铝,不锈钢,金属铜和镍样品中杂质元素含量,每个样品获得了约60个杂质元素的半定量分析结果。     

中子孔隙度刻度井杂质元素含量控制

针对中海油服建造85口中子孔隙度井的需要,提出了刻度井的岩石分析内容。通过蒙特卡罗模拟了一种补偿中子孔隙度测井仪在井径为200 mm的纯灰岩刻度井中的响应,得到了仪器的标准响应关系。在灰岩中掺入不同含量的杂质,模拟并计算了杂质元素含量的允许范围。     

化学气相沉积钨单晶管材表面{110}晶面构成分析

通过电解蚀刻和电子衍射分析了具有轴向[111]晶向的管状钼单晶基体化学气相沉积(CVD)钨单晶涂层的{110}晶面的构成。实验发现,当W单晶涂层的轴向具有[111]晶体取向时,通过电解蚀刻,在钨单晶涂层的表面可以获得高份额的{110}晶面。蚀刻出来的{110}晶面呈台阶结构,并同[111]     

铀矿石浓缩物中杂质元素含量分析

<正>在铀矿石浓缩物(UOC)的核法证研究中,杂质元素含量是非常重要的特征指纹信息之一。相较于核燃料循环中的其他核材料,UOC中有多种杂质元素,如稀土元素、铁、钛、硒、铼、铌、钽、钌等,这些杂质元素留存了大量的原矿石产地信息以及UOC的生产工艺信息。为准确分析UOC中杂质元素含量,需进行化学分离去除含量为65%以上的大量铀元素。此过程包含UOC的溶解、转     

EAST托卡马克激光吹气杂质注入系统控制系统设计及测试

开展托卡马克等离子体中杂质输运与杂质控制研究对于提升等离子体约束性能与保障装置安全有重要意义。为了在EAST(Experimental Advanced Superconducting Tokamak)托卡马克装置上开展杂质输运研究,需要发展一套用于注入示踪杂质粒子的激光吹气（Laser Blow-off,LBO）微量杂质注入系统。本文描述了一种用于EAST托卡马克装置上LBO系统的控制系统设计过程与测试结果。该系统采用了全新的自动控制流程,使得系统可以重复、定量地向EAST等离子体注入不同元素的示踪杂质粒子。该设计通过STM32单片机系统实现对聚焦透镜位移、激光器被触发时刻的准确控制,且激光光斑直径可调,以改变杂质注入量。测试结果显示,系统能快速检测到外触发信号并实现精确定时,激光光斑聚焦位置误差小于0.40 mm,达到激光吹气杂质注入实验要求。本研究对在EAST装置上开展等离子体杂质输运研究具有重要意义。     

低能Ar离子束辅助沉积Cu、Ag、Pt薄膜

采用低能Ar离子束辅助沉积方法,在Mo/Si(100)衬底上分别沉积Cu、Ag、Pt薄膜.实验发现,若辅助轰击的Ar离子束沿衬底法线方向入射,当离子/原子到达比为0.2时,沉积的Cu膜呈(111)晶向,而Ag、Pt膜均呈(111)和(100)混合晶向.当辅助轰击的Ar离子束偏离衬底法线方向45°入射时,沉积的Cu、Ag、Pt膜均呈(111)择优取向.采用Monte Carlo方法模拟能量为500 eV的Ar离子入射单晶Ag所引起的原子级联碰撞过程,分别算得Ar离子入射单晶Ag(100)面、(111)面时,Ar离子的溅射率与入射角和方位角的关系.对离子注入的沟道效应和薄膜表面的自由能对薄膜择优取向的影响作了初步的探讨和分析.     

萃取色层ICP-AES法测定八氧化三铀中的杂质元素

在核工业中，铀是重要的核燃料，核燃料中杂质元素的含量有严格要求。化学光谱法是分析铀及其化合物中杂质元素的重要方法之一。本工作将U3O8样品溶解后，采用萃取色层分离技术使杂质元素与铀基体分离，收集含杂质淋洗液，用IRIS／Adv全谱直读ICP光谱仪测定杂质元素。     

用共振核反应~(27)Al(p,γ)~(28)Si和SOS样品研究质子在固体Si中能损的同素异形效应

本文首次用具有衬底的薄膜Si样品SOS和共振核反应~(27)Al(p,γ)~(26)Si,于能量E_p=774keV和992keV,系统地研究了质子在固体中能损的结构效应问题。实验结果表明,对于MeV级的质子束,在Si元素固体的单晶、多晶、非晶中电子阻止本领有明显的差别,相对偏差至少大于5％,这个实验的测量误差小于3％。     

用背散射方法分析硅中注入砷的深度分布

用离子注入方法能快速地将一种杂质元素射入到半导体材料中,而杂质元素在材料中的浓度随深度的分布直接影响了材料的性能,因此准确测定它们是十分必要的。我们用背散射分析法分析了注入砷的硅样品。 1.实验方法和数据处理 样品是电阻率为7～15Ω·cm、〈111〉晶向的p型单晶硅。为避免沟道,约倾斜7°注入,经严格清洗后在氮气保护下,在不同退火条件下恒温退火。背散射实验工作是在原子能所静电加速器上进行的,选用     

波长色散X射线荧光光谱法快速测定铂铑合金中铂和铑的含量

采用波长色散X射线荧光(X-ray fluorescence,XRF)光谱法对铂铑合金中Pt和Rh的含量进行测定,建立了一种Pt和Rh的分析测量方法。实验设定波长色散XRF光谱仪激发电压为60 k V、电流为50 m A,采用100mm的黄铜滤光片、间距300mm的准直器、PX10分光晶体和闪烁探测器对Pt的La线和Rh的Ka线进行分析测量;为消除样品杯罩产生的干扰使用直径27 mm的准直器面罩。应用经验系数法对基体效应进行了校正,建立了Pt和Rh的校正曲线,其K值和RMS值(均方根偏差)较小,线性相关性较好。分析结果表明,Pt和Rh的相对误差分别小于0.09%和0.54%,相对标准偏差分别为0.11%和0.17%(n=10),检出限分别为208mg·g~(-1)和37mg·g~(-1),该方法能准确可靠地测定铂铑合金中Pt和Rh的含量,单样分析时间仅需74 s。将该方法应用到铂铑合金配制生产过程中,Pt和Rh的测定结果与配方值的相对误差分别小于0.06%和0.20%。在铂铑合金稀释熔炼中,对稀释后样品的Rh含量进行测量,其测量结果与计算值的相对误差低于0.29%。该方法能够满足大批量铂铑合金样品的分析需求,为生产实践提供准确可靠的科学数据。     

含杂质的卢瑟福散射的蒙特卡罗模拟

采用蒙特卡罗方法数值研究了杂质对α粒子卢瑟福散射的影响。杂质原子根据靶材的纯度以给定的概率随机替换靶材原晶格的原子。研究结果表明,考虑杂质后,出射粒子随散射角分布的曲线中形成了新的峰,峰的位置随杂质元素原子序数的增加向大角度方向移动;杂质的原子序数越低、含量越高,对卢瑟福散射出射粒子角分布的影响越明显;同时,入射粒子能量越低,杂质产生的峰对分布曲线的影响越明显。此外,对典型的C6+、N7+等重离子束的卢瑟福散射的模拟计算结果表明,重离子束对杂质有更好的分辨率。     

Measurement of plastic strain of polycrystalline material by electron backscatter diffraction

It is important to know the degree of plastic strain in order to evaluate the susceptibility and crack growth rate of stress corrosion cracking (SCC) in stainless steel and nickel based alloy, because SCC is enhanced by the cold work and causes many problems in nuclear power plant components. In this study, electron backscatter diffraction in conjunction with scanning electron microscopy is applied to measure the plastic strain imposed to stainless steel by tensile load. A new parameter, which quantifies the spread of the crystal orientation within individual grains arising due to dislocation accumulation during plastic deformation, is correlated with imposed plastic strain. The new parameter is called ‘crystal deformation’ and is determined from the spread in misorientation from the central grain orientation. It is confirmed that this parameter has a good correlation with plastic strain and is not affected by the data density of the crystal orientation map. The dislocation density distribution is also evaluated from the misorientation from the central orientation. Relatively high dislocation density was observed near grain boundaries and grain boundary triple points, which was consistent with the observed deterioration of EBSD pattern quality in those locations.     

Optimization of Uranium Dioxide Structure for Use in the Fuel Elements of a Thermionic Converter Reactor

The results are presented of an extra-reactor investigation of a change in the structure of the uranium dioxide in a high-temperature fuel element in the field of a temperature gradient using an electric heater. It is shown that the width of a columnar grain of the restructured dioxide can be decreased from the characteristic value 200–250 μm down to 100 μm using dioxide with thermally stabilized porosity with porosity up to 20%. The creep characteristics of columnar uranium dioxide within this width range of a columnar grain are presented. The calculations show that the deformation rate of fuel-element cladding made of the hardened single-crystal alloy W-Nb under the action of a swelling kernel decreases severalfold when the grain width decreases to 100 μm. __________ Translated from Atomnaya Energiya, Vol. 99, No. 4, pp. 264–268, October, 2005.     

Effect of irradiation on the deformation of copper and copper-aluminium alloys

The effect of low-temperature irradiation (<70°C) on the deformation of pure copper, Cu-0.09 wt% Al alloy, and Cu-0.19 wt% Al alloy was investigated. Tensile specimens were prepared from single crystals of various orientations, and were exposed to a neutron fluence of 6.85 ×10¹⁹ n/cm²(E>1 MeV) at a temperature less than 70°C. All irradiated and unirradiated specimens were pulled. A large increase in critical shear stress due to irradiation was observed; the increase was smaller in Cu-0.19 wt% Al alloy than in pure copper and Cu-0.09 wt% Al alloy. Ultimate shear stress and shear strain were less influenced by irradiation. Yield points were observed in all irradiated specimens. The yield drop was large in irradiated pure copper, and decreased with the increase of aluminium content in copper-aluminium alloys. All unirradiated specimens showed a high work-hardening coefficient (n) in the beginning of the deformation, followed by a lower value. By irradiation, the first value drastically decreased, while the second remained nearly constant. Shear stress and shear strain were influenced by crystal orientation.     

用同步辐射XRF和基本参数法分析

利用同步辐射Ｘ荧光分析技术，采用基本参数法，定量分析了单晶硅中掺杂元素Ｇｅ的含量。程序用标样进行了检验，误差小于１２％．     

How crystal configuration affects the position detection accuracy in pixelated molecular SPECT imaging systems?

It is well known that inter-crystal scattering and penetration(ICS-P) are major spatial resolution limiting parameters in dedicated SPECT scanners with pixelated crystal.In this study,the effect of ICS-P on crystal identification in different crystal configurations was evaluated using GATE Monte Carlo simulation.A ~(99m)Tc pencil-beam toward central crystal element was utilized.Beam incident angle was assumed to vary from 0° to 45° in 5° steps.The effects of various crystal configurations such as pixel-size,pixel-gap,and crystal material were studied.The influence of photon energy on the crystal identification(CI) was also investigated.Position detection accuracy(PDA) was defined as a factor indicating performance of the crystal.Furthermore,a set of ~(99m)Tc point-source simulations was performed in order to calculate peak-to-valley(PVR) ratio for each configuration.The results show that the CsI(Na)manifests higher PDA than NaI(TI) and YAP(Ce).In addition,as the incident angle increases,the crystal becomes less accurate in positioning of the events.Beyond a crystal-dependent critical angle,the PDA monotonically reduces.The PDA reaches 0.44 for the CsI(Na) at 45° beam angle.The PDAs obtained by the point-source evaluation also behave the same as for the pencil-beam irradiations.In addition,the PVRs derived from flood images linearly correlate their corresponding PDAs.In conclusion,quantitative assessment of ICS-P is mandatory for scanner design and modeling the system matrix during iterative reconstruction algorithms for the purpose of resolution modeling in ultra-high-resolution SPECT.     

Microdefects and 3d electrons in ordered B2-FeAl alloys investigated by positron annihilation techniques

Microdefects and 3d electrons in B2-FeAl alloys with different chemical composition, single crystal of Fe and cold-rolled Fe has been studied by positron lifetime and coincidence Doppler broadening spectroscopy. The coincidence Doppler broadening spectrum of the single crystal of Fe shows the highest 3d electron signal in the spectra of all tested samples. The 3d electron signal in the spectrum of Fe₅₀Al₅₀ alloy is much lower than that of the cold-rolled Fe. This indicates that some of the 3d electrons of Fe atoms and 3p electrons of Al atoms in B2-FeAl alloy are localized to form strong covalent bonds, thus decreasing the probability of positron annihilation with 3d electrons of Fe atoms. With the increase of Al content in B2-FeAl alloys, the 3d electron signal in the spectrum of the alloy decreases, while the open volume of defect increases.     

不同管径与倾角下单管和管束外含空气蒸汽冷凝对比分析

为评估不同传热管结构参数下单管与管束外含空气蒸汽冷凝传热规律的差异,基于外径12～19 mm、倾角0°～90°的单管和3×3管束在压力0.2～1.6 MPa、空气质量份额12%～87%的参数范围内开展了试验研究。结果表明：不同压力范围内,管径和倾角对单管和管束的影响呈现不同的规律。在压力小于0.8MPa时,管束冷凝传热受管径和倾角影响的规律与单管总体一致,两者的冷凝传热系数均随管径和倾角的减小而增大。在0.8～1.6 MPa时,管束冷凝传热受管径和倾角的影响与单管存在明显差异。结合不凝性气体影响蒸汽冷凝传热的机制对所呈现的一致性和差异性规律进行了分析。     

Space-resolved vacuum-ultraviolet spectroscopy for measuring impurity emission from divertor region of EAST tokamak

The measurement of impurity distribution in the divertor region of tokamaks is key to studying edge impurity transport. Therefore, a space-resolved vacuum-ultraviolet (VUV) spectrometer is designed to measure impurity emission in the divertor region on EAST. For good spectral resolution, an eagle-type VUV spectrometer with 1 m long focal length with spherical holograph grating is used in the system. For light collection, a collimating mirror is installed between the EAST plasma and the VUV spectrometer to extend the observing range to cover the upper divertor region. Two types of detectors, i.e. a back-illuminated charge-coupled device detector and a photomultiplier-tube detector, are adopted for the spectral measurement and high-frequency intensity measurement for feedback control, respectively. The angle between the entrance and exit optical axis is fixed at 15°. The detector can be moved along the exit axis to maintain a good focusing position when the wavelength is scanned by rotating the grating. The profile of impurity emissions is projected through the space-resolved slit, which is set horizontally. The spectrometer is equipped with two gratings with 2400 grooves/mm and 2160 grooves/mm, respectively. The overall aberration of the system is reduced by accurate detector positioning. As a result, the total spectral broadening can be reduced to about 0.013 nm. The simulated performance of the system is found to satisfy the requirement of measurement of impurity emissions from the divertor area of the EAST tokamak.