排序方式: 共有15条查询结果,搜索用时 15 毫秒
11.
本文用在位X-射线衍射技术研究了PAN(聚丙烯腈)纤维的预氧化过程。由广角测得不同温度下试样随热解时间而变化的一系列的解析谱图中计算出样品的结晶度、微晶尺寸、晶面间距和芳构化指数,并对这些参数随实验条件变化的瞬间情况给予了解释。同时,还描述了PAN纤维在预氧化过程中的环化动力学行为。求解了各温度下的环化反应速率和活化参数。 相似文献
12.
13.
A direct method is proposed to quantitatively characterize the structural depth profiles emerged in the polycrystalline thin films based on the information obtained by X-ray diffraction (XRD) with various incident angles and treated by a numerical procedure known as the constrained linear inversion. It should be noted that the proposed method was neither sensitive to the random noise appearing in experiment nor to the error originated from the measured thickness of the specimen. To testify the validity of the method, XRD measurements were carried out on a specially designed Pd/Ag bilayer sample, which was annealed at 490℃ for 20 min, and the depth profiles were accordingly calculated through resolving the obtained XRD patterns. The elemental concentration depth profile of the Pd/Ag bilayer sample was in turn calculated from the resolved patterns, which was in good agreement with those obtained by Auger electron analysis on the annealed sample. 相似文献
14.
A modified Bragg law for straightforward determining the film thickness by low-angle X-ray reflection was derived based on the geometrical optical theory. We showed that this modified Bragg law and its inference formulae could be used to accurately determine the thickness of the monolayer or multilayer film. Furthermore, the modified Bragg law for determining the superlattice period presented earlier by others can be derived from the above modified Bragg law. The similar inference formulae were also given. The precision in determining the film thickness and/or superlattice period by the above formulae was discussed. 相似文献
15.
对粉末法衍射线线位的重心法的误差问题,过去曾进行了大量的研究,得出了各种误差的定量校正计算公式,并有不少文章认为重心法的相对准确度(波长误差除外)最高[1-3] 本文提出重心法的一个新的误差项,这项误差来源于:(1)对于任何实际晶体,它的点阵常数的数值都有一分布,我们用“点阵常数(及晶面间距)分散度”表示.因此,任何晶面的衍射都由于此分布而具有一定的真实宽度.(2)衍射角与晶面间距的关系为非线性的.故此误差项,称为“点阵常数分散度误差”.具体如下: 由布喇格公式可得即在一条有一定真实宽度的衍射线内,相同的△(2θ)在高角度端对应… 相似文献