Al—Si—Mn—Fe合金中相组成的电子衍射鉴定

本文利用选区电子衍射,并结合X射线衍射对六种不同成份的急冷合金及其退火后的相组成进行了鉴定,得到了它们的相组成。     

柱形颗粒群直径分布的激光衍射测量技术

提出了用激光衍射功率谱方法测量柱形颗粒群直径分布的技术方法，解决了长颗粒随机排列时的功率谱探测，及数据快速优化方法等技术难题。此技术已地应用于由羊毛和化纤截成的柱形颗粒群直径分布的测量，实现结果证明了此技术的可行性和实用性。     

New cubane MOCVD precursors for gallium sulphide and gallium selenide: Synthesis of [(Et2MeC)GaS]4 and [(Me2EtC)GaS]4: Structural determinations of [(Et2MeC)GaS]4 by X-ray diffraction and [(tBu)GaSe]4 by electron diffraction

The gallium sulphide cubane compounds [(Me₂EtC)GaS]₄ and [(Et₂MeC)GaS]₄, have been synthesised, and their potential as MOCVD precursors for GaS is discussed. The molecular structure of [(Et₂MeC)GaS]₄ has been determined by X-ray diffraction. In addition, the vapour phase structure of the GaSe precursor, [(^tBu)GaSe]₄ has been determined by gas phase electron diffraction and is compared with that previously determined in the solid state by X-ray diffraction.     

Elastic and plastic contributions to X-ray Line broadening of InGaAsP/InP Heterostructures

The coherency state of MOCVD grown InGaAsP/InP double-heterostructure wafers was examined and their effects on the structural properties were determined in this study. Lattice mismatches were measured using {511} asymmetric and (400) symmetric x-ray reflections. The chemical lattice misfit and the elastic strain were also calculated. Misfit dislocations were examined by both x-ray topography and photoluminescence imaging. The x-ray full width at half maximum (FWHM) varied with the degree of mismatch. The largest FWHM was obtained for samples containing the misfit dislocations. It was found that FWHM is influenced not only by the plastic deformation, but also by the elastic strain. To model the dependence of the FWHM, the radius of curvature was measured, and its contribution to the x-ray line broadening was calculated. Also, the contribution from misfit dislocations was taken into account. This model assumes that the dislocations are planar and interact weakly with each other. Good agreement between measured and calculated values was obtained. Thus, it is concluded that the major contribution to x-ray line broadening ofelastically strained sample is the lattice curvature induced by misfit strain, and that the dominant factor affecting x-ray FWHM ofplastically deformed sample is lattice relaxation induced by misfit dislocation.     

钙—铈氟碳酸盐矿物中BmSn型新多型的发现及其微结构研究

利用Philips CM-12分析型透射电镜对四川昌北大型稀土矿床中钙铈氟碳酸盐矿物进行了研究。除证实氟碳钙铈矿(BS)存在3R和6R2种多型外,首次发现和研究了氟碳钙铈矿(BS)存在4H、12H、18R、24R、30R和36R6种新多型;伦琴矿(BS_2)1种6R新多型和B_2S新规则混层矿物2H、12R和24R3种中新多型。电子衍射和晶格象分析表明:该类矿物中众多新多型的产生,主要是由于矿物结构单元层沿(?)轴有序堆垛和[CO_3]的定向周期性变化所致。     

生物薄试样电镜X射线显微定量分析法进展

本文重点介绍应用Hall理论进行生物薄试样电镜X射线定量分析的原理和近年来运用此理论进行分析所采用的有关扣除背底、峰剥离、外源性背底校正以及标样等技术。文中还描述了“薄试样”的条件,介绍了近年运用Link公司开发的分析软件测定各元素的标样参数(FST)、根据标样参数对生物薄试样进行元素分析的方法。     

周期性动态热效应光栅的研究

为使激光诱导动态光栅产生在空间上可分辨的高效率衍射光，光栅介质必须足够薄以满足光栅条件，但动态光栅自衍射效率却又随介质厚度的增加而增加，我们提出用相位匹配的周期性薄光栅组可解决这一矛盾，并在实验上用周期性热效应光栅对理论进行了验证。     

Study of indium droplets formation on the InxGa1−xN films by single crystal x-ray diffraction

Indium droplet formation during the epitaxial growth of In_xGa_1−xN films is a serious problem for achieving high quality films with high indium mole fraction. In this paper, we studied the formation of indium droplets on the In_xGa_1−xN films grown by metalorganic chemical vapor deposition (MOCVD) using single crystal x-ray diffraction. It is found that the indium (101) peak in the x-ray diffraction spectra can be utilized as a quantitative measure to determine the amounts of indium droplets on the film. It is shown by monitoring the indium diffraction peak that the density of indium droplets increases at lower growth temperature. To suppress these indium droplets, a modulation growth technique is used. Indium droplet formation in the modulation growth is investigated and it is revealed in our study that the indium droplets problem has been partially relieved by the modulation growth technique.     

New developments in CdTe and CdZnTe detectors for X and γ-ray applications

There has been considerable recent progress in II-VI semiconductor material and in methods for improving performance of the associated radiation detectors. New high resistivity CdZnTe material, new contact technologies, new detector structures, new electronic correction methods have opened the field of nuclear and x-ray imaging for industrial and medical applications. The purpose of this paper is to review new developments in several of these fields. In addition, we will present some recent results at LETI concerning first the CdTe 2-D imaging system (20 × 30 mm² with 400 × 600 pixels) for dental radiology and second the CdZnTe fast pulse correction method applied to a 5 × 5 × 5 mm³ CdZnTe detector (energy resolution = 5% for detection efficiency of 85% at 122 keV) for medical imaging.     

Strain relaxation in silicon ion molecular beam epitaxy on silicon (001) substrates during aging

Silicon strained epitaxial films were grown on Si (001) substrates by low energy ion beam assisted molecular beam epitaxy. Films grown in the range of 450– 550°C with concurrent Ar⁺ ion bombardment (100 eV) were characterized using x-ray diffraction and transmission electron microscopy and found to be disloca-tion free and ununiformly strained. During aging, the strained layers stay stable until 500°C. Relaxation of most of the strain occurred at temperatures of 500-650°C. At higher aging temperatures, the strained layers relaxed by the formation of dense dislocation structures.