![]() The impact of background subtraction method has also been assessed. A new peak deconvolution method then is proposed to analyze cellulose XRD data with the amorphous Fourier model function in conjunction with standard Voigt functions representing the crystalline peaks. The amorphous XRD profile is modeled using a Fourier series equation where the coefficients are determined using the nonlinear least squares method. This agrees well with cellulose I d-spacing measurements and oligosaccharide XRD analysis. It is hypothesized that short range order within a glucose unit and between adjacent units survives ball milling and generates the characteristic amorphous XRD profiles. It first examines the effects of ball milling on three types of cellulose and results show that ball milling transforms all samples into a highly amorphous phase exhibiting nearly identical powder X-ray diffraction (XRD) profiles. polarisation to actually ‘show’ stress in transparent materials.This paper addresses two fundamental issues in the peak deconvolution method of cellulose XRD data analysis: there is no standard model for amorphous cellulose and common peak functions such as Gauss, Lorentz and Voigt functions do not fit the amorphous profile well. So X-ray diffraction is a technique to demonstrate mechanical stress in crystalline materials. Stress can result in broader peaks as well as in peak displacement towards a larger or smaller crystal plane spacing. After all, atoms in the lattice – and therefore crystal planes as well – are slightly pulled apart or squeezed together under stress. X-ray diffraction also allows you to check whether a material is subjected to mechanical stress. With a certain preferred orientation, certain crystal planes will reflect X-rays much more often than in the case of a random orientation, so that the peak associated with that crystal plane becomes larger. For a polycrystalline material, you can also say something about the crystallite size – smaller crystallites cause broader peaks – or about a possible preferred orientation of the crystallites. Using X-ray diffraction, you can determine so much more than only the crystal structure. X-ray diffraction can be carried out with single crystals, but also with polycrystalline materials that are ground into powders. For many known crystals, these patterns are available in a library, and by comparing a newly recorded diffraction pattern with the patterns in the library, you can find out which crystalline material you are dealing with. This X-ray diffraction pattern is characteristic for the crystal structure, a fingerprint indeed. A recorder measures the intensity of the reflected radiation, and this is expressed in a pattern with peaks at certain angles (2θ) or crystal plane distances. If you bombard a stationary crystal with X-rays from different incident angles, then there will be different crystal planes, each with their own crystal plane spacing, that successfully reflect the X-rays. This happens at a suitable combination of the incident angle θ under which the X-rays hit the plane, the wavelength λ of this radiation and the spacing d between adjacent lattice planes. In most directions, these reflected rays cancel each other, but in certain directions they reinforce each other. Where a normal mirror reflects visible light, the crystal planes act as a mirror for X-rays. This is radiation with a wavelength of about 1 Angstrom (10 -10 m), in the same order of magnitude as the distance between atoms in a crystal. You do this by bombarding the material with X-rays. X-ray diffraction (XRD) is an analysis technique to determine the crystal structure of crystalline materials. ![]()
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