Application of the pattern-fitting structure-refinement method of X-ray powder diffractometer patterns
Application of the pattern-fitting structure-refinement method of X-ray powder diffractometer patterns
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DOI：
10.1107/s0021889877013466
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发表时间：
1977-08
影响因子：
6.1
通讯作者：
R. Young;P. Mackie;R. Dreele
中科院分区：
文献类型：
--
作者：
R. Young;P. Mackie;R. Dreele
Rietveld发展的全图形最小二乘拟合法(这里称为图形拟合结构精化方法，PFSR)被许多人用来处理中子粉末数据，并已扩展到用于X射线粉末衍射仪数据。给出了五种不同空间群样品的PFSR算例。结构参数一般在2σ内与单晶结果一致。测定了LaPO_4、Ca5PO_4、3F和石英的原子位置和位置。R(模式)值一般在9%到20%之间，而R(Bragg)值较低几个百分点。反射轮廓用高斯或柯西函数表示：需要更好的表示，预期的结果是提高灵敏度并伴随较低的R值。展示了通过主相的PFSR改进用于次要相研究的模式剥离的可能性。作为额外的好处，获得了非常精确的晶格参数，例如，在氟磷灰石情况下，从所有低于2θ<；77°的数据中获得1/35000的点阵参数，以及对布拉格轮廓的衍射展宽的参数表征。
The whole-pattern least-squares fitting method (herein called the pattern-fitting structure-refinement, PFSR, method) developed by Rietveld and used by many with neutron powder data has been extended for use with X-ray powder diffractometer data. Examples of PFSR for specimens in five different space groups are given. Structural parameters generally agree, within 2σ, with those from single-crystal results where available. Atom positions and site occupancies were determined for LaPO4 Ca5PO4)3F, and quartz. R(pattern) values generally ranged from 9 to 20% while R(Bragg) values were a few percent lower. Reflection profiles were represented by either Gaussian or Cauchy functions: better representations are shown to be needed with an expected result of improved sensitivity accompanying lower R values. Possibilities for improved pattern-stripping for minor phase study via PFSR of the major phase are exhibited. Remarkably precise lattice parameters, e.g. 1 part in 35000 from data all below 2θ < 77° in the fluorapatite case, and parametric characterization of the diffraction broadening of the Bragg profiles are obtained as additional benefits.