Texture and structural refinement using neutron diffraction data from molybdite (MoO3) and calcite (CaCO3) powders and a Ni-rich Ni50.7Ti49.30 alloy

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2009-12

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Cambridge University Press

Abstract

Preferred orientation or texture is a common feature of experimental powder patterns. The mathematics of two commonly used models for preferred orientation-the March-Dollase and the generalized spherical-harmonic models-is reviewed. Both models were applied individually to neutron powder data from uniaxially pressed molybdite (MoO3) and calcite (CaCO3) powders in Rietveld analyses, as well as the as-received powders. The structural refinement results are compared to single-crystal structures. The results indicate that reasonable refinement of crystal structures can be obtained using either the March model or generalized spherical-harmonic description. However, the generalized spherical-harmonic description provided better Rietveld fits than the March model for the molybdite and calcite. Therefore, the generalized spherical-harmonic description is recommended for correction of preferred orientation in neutron diffraction analysis for both crystal structure refinement and phase composition analysis. Subsequently, the generalized spherical-harmonic description is extended to crystal structure refinement of annealed and the aged polycrystalline Ni-rich Ni50.7Ti49.30 shape memory alloys. (C) 2009 International Centre for Diffraction Data. [DOI: 10.1154/1.3257906]

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Keywords

preferred orientation, texture, neutron powder diffraction, march model, generalized spherical harmonics, molybdite, calcite, ti50.70ni49.30, shape memory alloy, shape-memory alloy, preferred orientation, rietveld refinement, x-ray, crystal-structure, phase, model, distributions, intensities, density, materials science, characterization & testing

Citation

Sitepu, H., "Texture and structural refinement using neutron diffraction data from molybdite (MoO3) and calcite (CaCO3) powders and a Ni-rich Ni50.7Ti49.30 alloy," Powder Diffr., Vol. 24(4), 2009. DOI: 10.1154/1.3257906