The effect of composition and cation ordering on the compressibility of columbites up to 7 GPa     

M. Pistorino  F. Nestola  T. Boffa Ballaran  M. C. Domeneghetti 《Physics and Chemistry of Minerals》2006,33(8-9):593-600

The unit-cell parameters of two columbite samples along the (Fe,Mn)Nb₂O₆ solid solution were measured by means of high-pressure single-crystal X-ray diffraction up to pressures of 7 GPa. The compressional behaviour of these minerals was studied as a function of composition and degree of order. The P–V data of all the samples were fitted with a third-order Birch–Murnaghan equation of state. For the two samples with different compositions but identical degree of order the substitution of Mn for Fe causes a decrease of the bulk modulus K _T0, from 153(1) to 146(1) GPa, without any effect on the pressure first derivative K′. For the two samples with the same composition, cation ordering causes an increase of the bulk modulus from 149(1) to 153(1) GPa and of the pressure first derivative from 4.1(2) to 4.8(3). The compressional behaviour is anisotropic with a linear axial compressibility scheme β _b > β _c ≥ β _a for all samples, regardless of composition and degree of order. Such anisotropy increases sligthly with increasing Mn content.  相似文献   

微量相X射线衍射定量分析的一种简便方法     

何泽能李振山  斯永敏 《岩矿测试》2005,24(2):81-86

阐述了关于微量相X射线衍射定量分析的一种简便方法———近似线性关系法,它适用于二相体系(或基体吸收系数基本恒定的多相体系)材料中微量相的定量分析。该方法不需要在待测样品中加入参考物相,分析时仅需对一条衍射线进行测定,因而分析时间很短,其测定结果与实际含量的相对误差为-10.2%～ 21.4%,与外标法和内标法的测量结果的精度相当。  相似文献   

理学3080E3型X射线荧光光谱仪维修实例   总被引：2，自引：0，他引：2  

唐晓慧 《岩矿测试》2005,24(3):237-238

介绍理学3080E3型X射线荧光光谱仪样品驱动单元及高压发生器部分的故障现象及维修实例。  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   

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   

A hybrid indirect boundary element—discrete wave number method applied to simulate the seismic response of stratified alluvial valleys     

S. A. Gil-Zepeda  J. C. Montalvo-Arrieta  R. Vai  F. J. Snchez-Sesma 《Soil Dynamics and Earthquake Engineering》2003,23(1):77-86

A hybrid indirect boundary element – discrete wavenumber method is presented and applied to model the ground motion on stratified alluvial valleys under incident plane SH waves from an elastic half-space. The method is based on the single-layer integral representation for diffracted waves. Refracted waves in the horizontally stratified region can be expressed as a linear superposition of solutions for a set of discrete wavenumbers. These solutions are obtained in terms of the Thomson–Haskell propagators formalism. Boundary conditions of continuity of displacements and tractions along the common boundary between the half-space and the stratified region lead to a system of equations for the sources strengths and the coefficients of the plane wave expansion. Although the regions share the boundary, the discretization schemes are different for both sides: for the exterior region, it is based on the numerical and analytical integration of exact Green's functions for displacements and tractions whereas for the layered part, a collocation approach is used. In order to validate this approach results are compared for well-known cases studied in the literature. A homogeneous trapezoidal valley and a parabolic stratified valley were studied and excellent agreement with previous computations was found. An example is given for a stratified inclusion model of an alluvial deposit with an irregular interface with the half-space. Results are displayed in both frequency and time domains. These results show the significant influence of lateral heterogeneity and the emergence of locally generated surface waves in the seismic response of alluvial valleys.  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   

X射线荧光测井井液的影响与校正     

葛良全  周四春  谢庭周  章晔  程业勋  侯胜利 《物探化探计算技术》1996,(S5)

X射线荧光测井中 ,井液位于井下探管与井壁之间 ,它的影响不但表现在对特征X射线的吸收 ,而且表现在对源初级射线和特征 X射线的散射。井液的校正采用硬件与软件相结合的方法 ,在硬件上 ,使含有探测器的部分制成单独的短臂 ,有效地保证了探测窗与井壁的良好接触 ;在软件上 ,提出的双散射峰法和散射峰 -逃逸峰法 ,能够校正 0 - 10 mm厚的井液对 X射线荧光测井结果的影响  相似文献   

Surface chemical analysis in coal preparation research: complementary information from XPS and ToF-SIMS     

A. N. Buckley  R. N. Lamb 《International Journal of Coal Geology》1996,32(1-4)

The application of X-ray photoelectron spectroscopy (XPS) to coal surface characterisation for preparation research is described. Progress towards the acquisition of complementary surface chemical information by time-of-flight secondary ion mass spectrometry (ToF-SIMS) is also discussed. Surface-based beneficiation techniques such as flotation are assuming greater importance as the proportion of fines in raw coal increases due to the proliferation of high capacity mining methods. A necessary condition for the floatability of a coal particle is adequate hydrophobicity, and the degree of hydrophobicity of the flotation concentrate is one factor influencing the ease with which its dewatering can be affected. The hydrophobicity of a coal is very difficult to measure directly because of microporosity, and it is often necessary to deduce the degree of hydrophobicity from a knowledge of the surface chemistry. XPS is able to provide sufficient analytical data to allow relative levels of hydrophobicity to be estimated. In principle, ToF-SIMS should be able to supply additional information enabling refinement of such estimates; however, there are insufficient data at present to allow the ionic fragments detected to be related to specific functional groups at the coal surface.  相似文献