Diffraction peaks, indexing

Figure 1 shows the powder X-ray diffraction (XRD) pattern of the as-prepared Li(Nio.4Coo.2Mno.4)02 material. All of the peaks could be indexed based on the a-NaFeC>2 structure (R 3 m). The lattice parameters in hexagonal setting obtained by the least square method were a=2.868A and c=14.25A. Since no second-phase diffraction peaks were observed from the surface-coated materials and it is unlikely that the A1 ions were incorporated into the lattice at the low heat-treatment temperature (300°C), it is considered that the particle surface was coated with amorphous aluminum oxide. 

For the evaluation of the response of the sensor, we selected several vapors of different polarity. The vapors included water (H20), acetonitrile (ACN), toluene, and dichloromethane (DCM). Solvent polarity and refractive index of tested vapors are listed in Table 4.346 47. The spectral range for the evaluation of the vapor responses of the colloidal crystal film was selected as 700 995 nm, which covered only the fundamental Bragg diffraction peak on the (111) planes of the colloidal crystal film to further reduce effects from possible stacking defects in the film as suggested in the literature44. 

The purpose of indexing texture patterns is the geometrical reconstruction of the three-dimensional reciprocal lattice from the two-dimensional distribution of H spacings. One advantage of texture patterns is the possibility to determine all unit cell parameters of a crystal unambiguously and index all the diffraction peaks from only a single texture... 

Note that the number of diffraction peaks decreases with time as the droplet diameter decreases, and the number density of peaks is very nearly proportional to the droplet size. The intensity of the scattered light also decreases with size. The resolution of the photodiode array is not adequate to resolve the fine structure that is seen in Fig. 21, but comparison of the phase functions shown in Fig. 22 with Mie theory indicates that the size can be determined to within 1% without taking into account the fine structure. In this case, however, the results are not very sensitive to refractive index. Some information is lost as the price of rapid data acquisition. 

The chemistry of Scheme 2 produces a cubic pore structure with long-range periodicity and unit cell parameter (Ko) of 8.4 nm. The material show a relatively large number of Bragg peaks in the X-ray diffraction (XRD) pattern, which can be indexed as (211), (220), (321), (400), (420), (332), (422), (431), (611), and (543) Bragg diffraction peaks of the body-centered cubic Ia-3d symmetry (Fig. 1). 

Figure 10 Phase identification of CuO nanowires, (a) An electron image of the wires, (b) the recorded diffraction pattern, (c) the diffraction intensity plotted as a function of sin 0/X and indexing diffraction peaks based on CuO monoclinic structure...

The correct solution must result in a high figure of merit (although not necessarily the highest) and most, if not all diffraction peaks should be indexed. Unindexed Bragg reflections must be explained, for example, by low intensity, by noticeably different peak widths, or they should be identified as corresponding to an impurity phase. 

For the high-quality MCM-41 sample, XRD can give more than four hkO diffraction peaks. Figure 8.13 shows the XRD pattern of high-quality MCM-41 made from an extremely low surfactant-concentration system.[110]. These peaks, except the first one, are very weak. The position of diffraction peaks can be indexed with 2-D hexagonal p6mm symmetry. 

Xiao[207] reported the preparation of ordered hexagonal mesoporous aluminosilicates (MAS-5) with uniform pore sizes from self-assembly of preformed aluminosilicate precursors with CTAB surfactant. The XRD pattern for a typical as-made MAS-5 sample shows four well resolved peaks that can be indexed as (100), (110), (200), and (210) reflections associated with the hexagonal symmetry. No diffraction peak was observed in the region of higher angles 10-40°, which indicates the absence of large... 

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