X射线衍射峰五基本要素的物理学意义与应用   总被引：6，自引：0，他引：6  

周健  王河锦 《矿物学报》2002,22(2):95-100

本文根据Bragg衍射方程、Scherrer方程、衍射强度计算原理，研究讨论了X射线衍射5构成要素中的衍射峰位置、衍射峰宽度、衍射峰高度的物理学意义。根据实验研究证明了衍射峰不对称性的几何条件特征，并用地质事实验证了衍射形态变化与晶格应变和粒度大小的内在联系。从而阐明了单个衍射峰5基本构成要素的完整物理学意义，并以实例论证了5要素的实际应用价值。  相似文献   

Thermal expansion and crystal structure of FeSi between 4 and 1173 K determined by time-of-flight neutron powder diffraction     

L. Vočadlo  K. S. Knight  G. D. Price  I. G. Wood 《Physics and Chemistry of Minerals》2002,29(2):132-139

The thermal expansion and crystal structure of FeSi has been determined by neutron powder diffraction between 4 and 1173?K. No evidence was seen of any structural or magnetic transitions at low temperatures. The average volumetric thermal expansion coefficient above room temperature was found to be 4.85(5)?×?10^?5?K^?1. The cell volume was fitted over the complete temperature range using Grüneisen approximations to the zero pressure equation of state, with the internal energy calculated via a Debye model; a Grüneisen second-order approximation gave the following parameters: θ_D=445(11)?K, V ₀=89.596(8)?ų, K ₀′=4.4(4) and γ′=2.33(3), where θ_D is the Debye temperature, V ₀ is V at T=0?K, K ₀′ is the first derivative with respect to pressure of the incompressibility and γ′ is a Grüneisen parameter. The thermodynamic Grüneisen parameter, γ_th, has been calculated from experimental data in the range 4–400?K. The crystal structure was found to be almost invariant with temperature. The thermal vibrations of the Fe atoms are almost isotropic at all temperatures; those of the Si atoms become more anisotropic as the temperature increases.  相似文献   

喉癌CT分型和CD44V6表达的意义     

孙伟英  袁建华  施明英 《CT理论与应用研究》2002,11(1):17-19

目的 探讨喉癌的CT分型和转移相关因子CD44V6表达的意义。方法 对39例喉鳞癌行术前常规CT检查，其术后标本进行CD44V6的表达检测，与术前CT片作对照分析。结果39例喉鳞癌CT检查；声门型24例，声门上型14例，跨声门型1例，声门下型0例；T1－2级22例，T3－4级17例；淋巴结转移组13例，非转移组26例，CD44V6总的阳性表达率为61．5％，对各组均采用秩次检验分析，CD44V6在喉癌的CT的T分级和淋巴结分组中存在显著性差异（P＜0．01）。而部位分区无明显差异。结论 喉癌的CT分型中的T分级、淋巴结分组与CD44V6的阳性表达密切相关。  相似文献   

不同浓度Li2SO4水溶液结构的X射线衍射研究          下载免费PDF全文

房艳  房春晖  高世扬 《盐湖研究》2003,11(2)

用θ～ 2θ型粉末衍射仪反射法精确测量了不同浓度的Li2 SO4水溶液的衍射数据 ,通过数据处理给出了溶液的结构函数和径向分布函数 ,由几何结构模型的最小二乘法精修 ,得到了溶液中阳离子和阴离子第一、二水合层的结构参数。  相似文献   

ARL9400型X荧光光谱仪探测器高压部分故障分析与维修     

吴红旗 《岩矿测试》2003,22(4):307-309

简述了瑞士ARL 9400型X荧光光谱仪探测器高压部分的故障现象、分析与处理及维修方法，并给出了维修实例。  相似文献   

滑带土粘土矿物定向性的x射线衍射及其对滑坡的作用   总被引：6，自引：1，他引：6  

王洪兴  唐辉明  陈聪 《水文地质工程地质》2003,(Z1)

本文首先论述了粘土矿物颗粒定向排列测定的基本原理并提出粘土矿物定向性定量评价方法,然后根据实例—庙上北滑坡的滑带土粘土矿物的X射线衍射结果,进行定向性定量分析计算,得出滑带土粘土矿物颗粒的定向度为弱到中等定向,并以中等定向为主。因而在水的往返作用下,滑带土具一定的胀缩性及胀缩的不均匀性,再加上粘土矿物本身亦具有的胀缩性及胀缩的可逆性和循环性,故导致滑带土抗剪强度和结构强度不断降低,大大影响斜坡的稳定性。  相似文献   

Kinetic study of the dehydroxylation of chrysotile asbestos with temperature by in situ XRPD   总被引：6，自引：0，他引：6  

A. Cattaneo  A. F. Gualtieri  G. Artioli 《Physics and Chemistry of Minerals》2003,30(3):177-183

 The kinetics of the dehydroxylation of chrysotile was followed in situ at high temperature using real-time conventional and synchrotron powder diffraction (XRPD). This is the first time kinetics parameters have been calculated for the dehydroxylation of chrysotile. The value of the order of the reaction mechanism calculated using the Avrami model indicates that the rate-limiting step of the reaction is a one-dimensional diffusion with an instantaneous nucleation or a deceleratory rate of nucleation of the reaction product. Hence, the rate-limiting step is the one-dimensional diffusion of the water molecules formed in the interlayer region by direct condensation of two hydrogen atoms and an oxygen atom. The calculated apparent activation energy of the reaction in the temperature range 620–750 °C is 184 kJ mol⁻¹. The diffusion path is along the axis of the fibrils forming the fibers. The amorphous or short-range ordered dehydroxylate of chrysotile is extremely unstable because forsterite readily nucleates in the Mg-rich regions. Moreover, it is less stable than the dehydroxylate of kaolinite, the so-called metakaolinite, which forms mullite at about 950 °C. This difference is interpreted in terms of the different nature of the two ions Mg²⁺ and Al³⁺ and their function as glass modifier and glass-forming ion, respectively. Received: 10 April 2002 / Accepted: 7 January 2003 Acknowledgements This work is part of a COFIN project (04 Scienze della Terra, NR 17, 2000) supported by MURST. Dr Dapiaggi is kindly acknowledged for help during the data collection at the Dipartimento di Scienze della Terra, University of Milan.  相似文献   

From geometry to dynamics of microstructure: using boundary lengths to quantify boundary misorientations and anisotropy   总被引：1，自引：0，他引：1  

John Wheeler  Z. Jiang  D. J. Prior  J. Tullis  M. R. Drury  P. W. Trimby 《Tectonophysics》2003,376(1-2):19-35

The microstructure of a quartzite experimentally deformed and partially recrystallised at 900 °C, 1.2 GPa confining pressure and strain rate 10⁻⁶/s was investigated using orientation contrast and electron backscatter diffraction (EBSD). Boundaries between misoriented domains (grains or subgrains) were determined by image analysis of orientation contrast images. In each domain, EBSD measurements gave the complete quartz lattice orientation and enabled calculation of misorientation angles across every domain boundary. Results are analysed in terms of the boundary density, which for any range of misorientations is the boundary length for that range divided by image area. This allows a more direct comparison of misorientation statistics between different parts of a sample than does a treatment in terms of boundary number.The strain in the quartzite sample is heterogeneous. A 100×150 μm low-strain partially recrystallised subarea C was compared with a high-strain completely recrystallised subarea E. The density of high-angle (>10°) boundaries in E is roughly double that in C, reflecting the greater degree of recrystallisation. Low-angle boundaries in C and E are produced by subgrain rotation. In the low-angle range 0–10° boundary densities in both C and E show an exponential decrease with increasing misorientation. The densities scale with exp(−θ/λ) where λ is approximately 2° in C and 1° in E; in other words, E has a comparative dearth of boundaries in the 8–10° range. We explain this dearth in terms of mobile high-angle boundaries sweeping through and consuming low-angle boundaries as the latter increase misorientation through time. In E, the density of high-angle boundaries is larger than in C, so this sweeping would have been more efficient and could explain the relative paucity of 8–10° boundaries.The boundary density can be generalised to a directional property that gives the degree of anisotropy of the boundary network and its preferred orientation. Despite the imposed strain, the analysed samples show that boundaries are not, on average, strongly aligned. This is a function of the strong sinuosity of high-angle boundaries, caused by grain boundary migration. Low-angle boundaries might be expected, on average, to be aligned in relation to imposed strain but this is not found.Boundary densities and their generalisation in terms of directional properties provide objective measures of microstructure. In this study the patterns they show are interpreted in terms of combined subgrain rotation and migration recrystallisation, but it may be that other microstructural processes give distinctive patterns when analysed in this fashion.  相似文献   

Raman scattering and X-ray diffraction study of the thermal decomposition of an ettringite-group crystal     

S. K. Deb  M. H. Manghnani  K. Ross  R. A. Livingston  P. J. M. Monteiro 《Physics and Chemistry of Minerals》2003,30(1):31-38

 A Raman scattering and X-ray diffraction study of the thermal decomposition of a naturally occurring, ettringite-group crystal is presented. Raman spectra, recorded with increasing temperature, indicate that the thermal decomposition begins at ≈55 °C, accompanied by dehydration of water molecules from the mineral. This is in contrast to previous studies that reported higher temperature breakdown of ettringite. The dehydration is completed by 175 °C and this results in total collapse of the crystalline structure and the material becomes amorphous. The Raman scattering results are supported by X-ray diffraction results obtained at increasing temperatures. Received: 9 July 2001 / Accepted: 14 August 2002  相似文献   

Advances in energy-dispersive X-ray fluorescence   总被引：1，自引：0，他引：1  

Utz Kramar 《Journal of Geochemical Exploration》1997,58(1):73-80

Recently, two new instruments for X-ray fluorescence analysis (XRF) with interesting features for geochemical applications came to the market. Both instruments were designed to improve the peak to background ratio, the principal factor limiting the sensitivity of XRF. Total reflection XRF (TXRF) was designed to analyse extremely small sample amounts. An instrument, using polarised X-rays (P-XRF) for excitation, is designed to reduce scattered background in spectra of bulk samples. The performance of both instruments was compared with conventional XRF-methods and ICP/MS. Results for GXR-1, GXR-2, GXR-3, GXR-4 and GXR-6 obtained with TXRF and P-XRF are in good agreement with literature data. The effective amount of sample, analysed by TXRF was 200 μg only and detection limits of ~ l μg/g were achieved. P-XRF shows considerable improved detection limits (0.25–0.5 μg/g) for bulk samples for elements with atomic numbers 42–51 (Mo-Sb) compared with conventional XRF-methods.  相似文献