RIETVELD REFINEMENT OF DEBYE-SCHERRER SYNCHROTRON X-RAY DATA FROM AL2O3
RIETVELD REFINEMENT OF DEBYE-SCHERRER SYNCHROTRON X-RAY DATA FROM AL2O3
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DOI：
10.1107/s0021889887087090
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发表时间：
1987-04-01
影响因子：
6.1
通讯作者：
HASTINGS, JB
中科院分区：
文献类型：
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作者：
THOMPSON, P;COX, DE;HASTINGS, JB
Rietveld精化技术的应用同步辐射X射线数据收集从毛细管样品的氧化铝在Debye-Scherrer几何描述。这些数据是在康奈尔高能同步辐射源（CHESS）上用Si（111）双晶单色器和Ge（111）晶体分析仪获得的。拟合到多个良好分辨的单个峰表明，峰形状由伪Voigt函数很好地描述，伪Voigt函数是高斯函数和洛伦兹函数的卷积的简单近似。高斯和洛伦兹半宽ΓG和ΓL随布拉格角的变化可以非常接近地用函数Vtan θ和X/cos θ来近似，它们分别代表仪器分辨率和粒子尺寸展宽的贡献。基于此模型的Rietveld精化得到了令人满意的结果。V和X的精确值与预期的垂直发散度（≤ 0.1 mrad）和标称粒度（≤ 0.3μm）一致。特别是，毛细管试样的使用几乎消除了优选的取向效应，这是非常显着的，在平板样品的这种材料。
The application of the Rietveld refinement technique to synchrotron X-ray data collected from a capillary sample of Al2O3 in Debye–Scherrer geometry is described. The data were obtained at the Cornell High Energy Synchrotron Source (CHESS) with an Si(111) double-crystal monochromator and a Ge(111) crystal analyzer. Fits to a number of well resolved individual peaks demonstrate that the peak shapes are very well described by the pseudo-Voigt function, which is a simple approximation to the convolution of Gaussian and Lorentzian functions. The variation of the Gaussian and Lorentzian half widths, ΓG and ΓL, with Bragg angle can be approximated quite closely by the functions V tan θ and X/cos θ which represent the contributions from instrumental resolution and particle-size broadening respectively. Rietveld refinement based on this model yields generally satisfactory results. The refined values of V and X are consistent with the expected vertical divergence (≃0.1 mrad) and the nominal particle size (≃ 0.3μm). In particular, the use of a capillary specimen virtually eliminates preferred orientation effects, which are highly significant in flat-plate samples of this material.