Quantitative Phase‐Composition Analysis of Liquid‐Phase‐Sintered Silicon Carbide Using the Rietveld Method

Abstract

Accurate quantitative X-ray diffraction analysis of SiC-based ceramics is difficult because of the significant overlap of the Bragg reflections from the different SiC polytypes. In this regard, the Rietveld method is a powerful tool for the accurate and precise analysis of the phase/polytype compositions in these materials. In this study, we have used two different types of Rietveld codes for the quantitative phase/polytype analysis of a liquid-phase-sintered SiC specimen: FULLPROF, which is based on the classical Rietveld approach, and BGMN, which is based on the new fundamental parameter approach. In both cases, the effect of texture corrections on the precision of the analysis also was studied. The accuracy of the analysis, in terms of the weight percentage of SiC (all polytypes) and yttrium aluminum garnet liquid phase, as determined from the starting powder composition, is within the standard deviation of the analysis in both cases (FULLPROF and BGMN), with and without the texture corrections. In addition, in the case of the classical code (FULLPROF), inclusion of the texture corrections has been shown to improve the precision. In contrast, the precision of the analysis using the BGMN code without the texture corrections is better. However, inclusion of the texture corrections is expected to improve the accuracy of the analysis.

Modelling soil surface charge density using mineral composition

“…Estimated standard deviations were derived from the estimated standard deviations on individual scale factors for the respective phases, excluding other error contributions. One must remember that standard deviation of refined Rietveld parameters is related to their precision rather than their accuracy; thus, accurate estimation of the errors in the quantitative phase-composition analysis requires the use of standard mixtures (Ortiz et al, 2000). The total surface area of soil minerals depends on both internal and external surface areas.…”

Structural characterization of a coarsegrained transparent silicon carbide powder by a combination of powder diffraction techniques

“…It is this huge difference in the phase abundance of the major and minor polytypes together with the extreme size and lattice perfection of the SiC crystallites -that distinguishes the SiC material investigated in the present work from those analyzed in previous powder diffraction investigations, see e.g. [4], which had reported in detail on the phase quantification of micron-sized, commercial SiC powders by applying the Rietveld method to diffraction patterns collected with conventional X-ray powder diffraction instrumentation an analytical technique rather unsuited for the given SiC material.…”

Nickel-containing di-charged imidazolium ligand with high crystalline organization. Interception and characterization of a transient carbene/cation species

“…The characterization of the crystalline structure of compound 2 is important for the prediction the behavior of 3D organization as well as understanding the influence of different parameters in the process. To understand this process, the relative apparent crystallinity variation was investigated at different temperatures by means of the ''fullprof'' code [22]. According to Hermans et al [23] the relative crystallinity is related with the area values by Eq.…”