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Potential of full pattern fit methods for the texture analysis of geological materials: implications from texture measurements at the recently upgraded neutron time‐of‐flight diffractometer SKAT
Author(s) -
Keppler Ruth,
Ullemeyer Klaus,
Behrmann Jan H.,
Stipp Michael
Publication year - 2014
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576714015830
Subject(s) - texture (cosmology) , neutron diffraction , powder diffractometer , diffraction , materials science , neutron , sample (material) , diffractometer , mineralogy , optics , analytical chemistry (journal) , geology , physics , computer science , chemistry , artificial intelligence , nuclear physics , image (mathematics) , scanning electron microscope , thermodynamics , chromatography
The application of Rietveld texture analysis (RTA) to time‐of‐flight (TOF) neutron diffraction data allows complex materials with many diffraction peaks to be investigated, for example, rocks composed of different minerals. At the recently upgraded SKAT texture diffractometer at the JINR in Dubna (Russia), which provides three alternative multidetector systems, resolution and accessible range of lattice d spacings can be adapted to sample requirements. In order to infer the optimum experimental setup and the reliability of texture estimates from complicated TOF patterns, the influence of counting statistics and various spectral resolutions on texture deconvolution was investigated. Comparing the results obtained at different resolutions and from different sections of the d patterns indicates that the textures of a four‐phase sample can be determined, but using a section at small d spacings with a larger number of peak overlaps leads to smoother textures. A complex seven‐phase sample shows orientation differences in addition to the smoothing effect. Weak textures and textures of the minor rock constituents are inaccurate owing to multiple peak overlaps. Consequently, good resolution is essential for RTA on such samples. Grid thinning tests confirmed that no more than 150 diffraction spectra are needed to characterize the texture of a monomineralic sample, and approximately 350 spectra are sufficient for a four‐phase sample. The irregular grid point arrangement caused by the SKAT geometry has no negative consequences.