Powder x-ray diffractograms

The analysis of XRPD patterns is an important tool studying the crystallographic structure and composition of powder compounds including the possibility to study deviation from ideal crystallinity, i.e. defects. Looking at an X-ray powder diffractogram the peak position reflects the crystallographic symmetry (unit cell size and shape) while the peak intensity is related to the unit cell composition (atomic positions). The shape of diffraction lines is related to defects , i.e. deviation from the ideal crystallinity finite crystallite size and strain lead to broadening of the XRPD lines so that the analysis of diffraction line shape may supply information about sample microstructure and defects distribution at the atomic level. 

Figure 1 X-ray powder diffractograms of the crystalline and amorphous forms of nedocromil sodium trihydrate. I is the intensity of the diffracted beam at a diffraction angle 9. (RK Khankari and DJW Grant, unpublished observations.)...

The small difference in energy between S4 and Ci forms caused speculations as to whether a second crystalline form might exist which has S4 symmetry. These assumptions were fed by the fact that an X-ray powder diffractogram revealed another orthorhombic lattice with half of the volume. This polymorphic form emerged when cooling below the... 

An advantage of the constant composition technique is that relatively large extents of growth and enhanced crystallinity can be achieved at low supersaturations. Improved crystallinity of the particles during crystallization is reflected in lower specific surface areas of the solid phases x-ray powder diffractograms of the solid phases removed from the crystallization cell also show increases in sharpness. Experiments in which crystal growth was allowed to proceed until five or six times the amount of... 

Figure 13 X-ray powder diffractograms of methylprednisolone sodium succinate in mannitol during stress testing at 40°C, showing crystallization of mannitol during storage (A) initial freeze-dried powder (B) two months and (C) six months.

Figure 5.4 X-ray powder diffractogram recorded for (a) A-type amylodextrins and (b) B-type amylodextrins grown as spherulites. X-ray fiber diffraction patterns (fiber axis vertical) for (c) A-amylose (fiber spacing 1.04 nm) and (d) B-amylose (fiber spacing 1.05 nm). (Reproduced with permission from references 30 and 31). Microcrystal of (e) A-starch and (f) B-starch observed by low dose electron microscopy. Inset the electron diffraction diagrams recorded under frozen wet conditions (e). (Reproduced with permission from references 32 and 34)...

The chemical analysis of the synthesized samples expresses in the framework composition, that is, (MeIAlyPz)02 provides the as-synthesized sample framework composition, which is shown in Table 3.7, indicating the presence of about 1% of Me in the synthesized aluminophosphate [29], From the x-ray powder diffractograms (Figure 3.14), it is noted that the crystallized products exhibit all the characteristic reflections of the MeAPO-5 molecular sieves [140] and a high crystallinity and degree of purity [29],... 

Figure 2. X-ray powder diffractogram of mesoporous silica, particle size 1.8 pm, template n-hexadecylamine, the Bragg peak corresponds to a d-spacing of 4.10 nm.

Formation of Pd-Ag alloy (Cat. C) and the presence of PdCx phase after poisoning were analyzed by X-ray diffraction. CuKa X-ray powder diffractograms were recorded with a Guinier camera equipped with curved quartz monocromator. 

D. G. Cameron and E. E. Armstrong, Optimization of stepsize in X-ray powder diffractogram collection. Powder Diff., 1988, 3, 32-37 (also ICDD, Methods Practices). 

X-Ray powder diffractograms contain in encrypted form information about the structure of the sample material. The positions and intensities of diffraction peaks reveal the information about an ideal crystal structure. The form of the peaks reflects the information about defects in the strncture. Instrumental aberrations affect the apparent peak positions (especially at low and high scattering angles) and intensities of the diffraction peaks as well as the form of the peaks.Hence, properly taking into account the instrumental contributions is essential both for studies aimed at obtaining information about the ideal crystal structure of the material and information about deviations from this ideal structure. 

Fig. 8-9. X-ray powder diffractograms of the precipitation products of Fe in the FCCI2-NH4OH system at pH 8.0 and at initial solution Mn/Fe molar ratios of (a) 0, (b) 0.1, (c) 1.0, and (d) 10.0 M = maghemite (Krishnamurti and Huang, 1989).

Figure 8. X-ray powder diffractograms of the 2,5-diheptyl-substituted PV-oligomers (n = 2 - 5) and of the monomer...

Some data on the phases, forming in these systems, have been obtained (Table III). The difference in the pressures of the evolving gas for the DTA method(a sealed ampoule) and TG-analysis (a labyrinth sample holder) accounts for the difference in the decomposition temperatures for [NiBi X2] and [NiB X2] B. X-Ray powder diffractograms showed that Ni- and Co-clath-rates are isostructural and differ from Zn and Cd-clathrates, differing from each other. 

Figure 4 shows the X-ray powder diffractograms of typical Na-SH materials together with a schematic illustration of the changes in the thickness of the bulk silicate layer. All reactions that characterize the M-SH (e.g dehydration, ion exchange, intercalation) proceed in the interlayer space. The basal spacing tt, therefore, varies, but the principle structure of the bulk layer remains unchanged. 

Fig. 3 shows the low-angle X-ray diffraction patterns of the calcined porous host silica MCM-41 curve 1, after modification with triethoxysilane -sample MCM-H curve 2 and the calcined sample MCM-41-Ag contained 2.0 wt% Ag curve 3. The x-ray powder diffractogram of the initial MCM-41 silica sample exhibits (100), (110), and (200) reflections in a low angle range... 

The preparations were characterized by ion exchange capacity (lEC), Al and Ni content. X-ray powder diffractogram (XRD), acidity, specific surface area and porosity. 

Figure 2. X-Ray powder diffractograms of native potato starch priori to illumination (native) and that starch (PPLN) after illumination for 5, 15, 25 and 50 hours.

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