The reference intensity ratio,I/I_c, for computer simulated powder patterns

Abstract

A scale factor 7, to convert from the relative to the absolute/relative intensity scale, is readily calculated during computer simulation of powder patterns. Previously used scale factors are related to 7. The Reference Intensity Ratio, I/Ic (c = corundum), is obtained from ~, e, and 7 for the sample and for corundum. Comparing calculated and experimental I/lc values confirms that microabsorption and primary extinction can be serious experimental aberrations possibly limiting the accuracy to several wt.% in quantitative analysis by powder diffraction.

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

“…Of course, the same advantage is present when integrated intensities are obtained by calculation but in this case the deconvolution of overlapping peaks in complex diffraction patterns remains a serious limitation of the method. To date, the general utility of both the calculated-constant and fitted-profile (Rietveld) methods has been diminished by (i) confusion about the definition of 'absolute', 'relative', and 'instrumental' scale factors (Hubbard et al, 1976) and (ii) problems associated with the treatment of preferred orientation (Weiss et al, 1983) and absorption (Hubbard et al, 1976;Werner et al, 1979).…”

“…Calibration of the relationship between peak intensity and phase abundance [i.e. determination of the value of Rp in (1)] is usually executed empirically, but increasing use is being made of constants derived from calculated diffraction-peak intensities (Hubbard, Evans & Smith, 1976;Alexander, 1977;AltreeWilliams, 1978;Hill, 1982). The use of calculated intensities has much to commend it since the constants are then derived from an ideal model in which the sample is composed of perfectly ordered and randomly oriented crystallites (unless deliberately altered), providing a 'standard' pattern free from preferred-orientation, extinction, surface-roughness and amorphous-component effects.…”

Microstructural evolution during high-temperature oxidation of spark plasma sintered Ti2AlN ceramics

“…JADE software (Materials Data Inc., Livermore, CA, US) was used to refine the lattice parameters from XRD peaks. Quantitative analysis was carried out using the Reference Intensity Ratio (RIR) method [19,20]. International Centre for Diffraction Data (ICDD) used are Oberkochen, Germany) operated in secondary electron imaging (SEI) and backscattered electron imaging (BEI) modes, coupled with energy-dispersive spectroscopy (EDS) for chemical analysis (Oxford Instruments INCA, Oxford, UK, using an ultra-thin window (UTW) detector which is capable of detecting light elements with atomic numbers Z>4).…”

New neutron time-of-flight (TOF) capability in PDF-4+ relational databases: digitized diffraction patterns and I/Ic for quantitative phases analysis

“…As an important adjunct for these methods, calculated I/I c have also been supplied for quantification phase identification. Hubbard et al (1976) have developed I/I c relations for X-rays. We have extended this treatment to consider both neutron constant wavelength (CW) data and neutron TOF data.…”

“…Corundum was selected as a reference material and its use in the PDF is ubiquitous. The reference intensity ratio (RIR), I/I c , is obtained from corundum data and the X-ray diffraction quantification of I/I c is available from the work of Hubbard et al (1976). In this paper, we specifically define the TOF derived I/I c as TOF-I/I c and extend this technology to TOF powder diffraction data.…”