Research Of Rietveld Method In Refinement Of Crystal Structure And Quantitative Phase Analysis

Rietveld whole-pattern fitting method using X-ray powder diffraction data is an efficient method in materials science research.In this paper,the computer program TOPAS based on this principle was used to explore some of the applications of the Rietveld method in the field of inorganic materials,including refinement of crystal structure and quantitative phase analysis(QPA).1.Refinement of crystal structureThe crystal structure of BaTiO3 and PbSO4 was refined by TOPAS using X-ray powder diffraction data. The profile function set up for this Rietveld refinement is the one with the pseudo-Voigt description of the profile shape.March–Dollase formulation was used for preferred orientation correction.The BaTiO3 crystallizes in the trigonal space group P4mm ( 99 ) with the following crystallographic parameters: a=3.9950473?,c=4.0253999?. The final refinement gives results with Rp=7.98%,Rwp=12.08%,Rexp=10.45%.The PbSO4 crystallizes in the orthorhombic space group Pbnm ( 62 ) with the following crystallographic parameters: a=6.957953? ,b=8.476731?,c=5.398124?. The final refinement gives results with Rp=7.62%,Rwp=10.33%,Rexp=7.42%2.Quantitative phase analysisThe quantitative analysis of specimens,which were the mixture powder of Al2O3 and ZnO with different weight ratios,were studied by using TOPAS computer program.The results are almost consistent with the original weight ratios of Al2O3 and ZnO in the specimens.It means Rietveld whole-pattern fitting method can validly be used for the quantitative phase analysis of multiphase powder.