Diffractogram, XRD

FIGURE 2.9 X-ray diffractogram (XRD) spectra of unmodified and modified nanoclays and styrene-butadiene rubber (SBR)-based nanocomposites with styrene content of (a) 15% and 40% and (b) 23%. (From Sadhu, S. and Bhowmick, A.K., J. Polym. Set, Part B Polym. Phys., 42, 1573, 2(304. Courtesy of Wiley InterScience.)... 

Table 1 also lists amount of O2 adsorption uptake, phase observed by X-ray diffractograms (XRD), and apparent oxidation number of the Mo, after reduction. O2 uptake for the catalyst reduced at 773 K was similar to that for the catalyst reduced at 673 K. The higher activity of the catalyst reduced at 773 K, seems to be related to the higher metallic Mo content. However, reduction at 873 K resulted in the formation of large amount of metallic Mo, leading to the catalyst producing hydrocarbons predominantly. This is in agreement with the effect of Mo precursors (ref. 7) and the order of... 

A typical in situ series of X-ray diffractogram (XRD) data for milled MgH2 heated from 150°C to 600°C at 10°Cmin under He. A scan from 24 to 38 in 26 was taken every 50 °C, (Croston, 2007). 

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. XRD pattern of an EMD sample (Chemetals). The diffractogram is taken with a Bruker AXS D5005 diffractometer using CuKa radiation and a scintillation counter. The step width is 0.02° with a constant counting time of 10 s / step.

IR spectra did not show differences between the intermediate phase and the disordered cancrinite. Therefore, IR techniques fail when were used to identify these phases. One more effective way to identify disordered cancrinite and the intermediate phase is by using X-ray diffraction (XRD). Fig 1 shows the diffractogram of both tectosilicates. In the intermediate phase, the observed peaks correspond with those reported in the literature[4]. The main differences between both spectra correspond to those peaks placed between 25°<20<35°, which are more intense for the disordered cancrinite [9]. Likewise, the results of specific surface area for the intermediate phase (sample 5) and the disordered cancrinite (sample 6) were 35 and 41 m2/g respectively. The antacid capacity test was carried out with the samples 5 and 6. Fig. 2 shows the relationship between experimental pH versus the mass content of the tectosilicates. The neutralization capacity of these solids is related with its carbonate content which reacts with the synthetic gastric juice to neutralize it. In general, the behaviour of solids is similar the pH increases as the weight of the studied solid is increased. However, a less disordered cancrinite mass amount must be employed to reach a pH= 4 in comparison... 

The powder X-ray diffractograms of the composites present the characteristic peaks of the encapsulated zeolite [9]. It is interesting to observe that no characteristic peak of chitosan was present in the XRD patterns of composites. It is clear that the presence of the zeolites has prevented the crystallisation of chitosan when the gel has been dried. This phenomenon has been already observed when the zeolite content reaches a threshold value and has been attributed to a strong interaction between zeolite and chitosan [10],... 

Figure 6.19 Catalytic in situ reactor made of a quartz capillary, suitable for use at synchrotrons for the collection of EXAFS an XRD data. The scheme of the synchrotron beamline shows the positions of the mono-chromator, the ion chambers which measure the intensity of the X-rays before and after the sample, and the position-sensitive X-ray detector which records the XRD diffractogram (adapted from Clausen [44]).

The examples are shown in Figure 9.1.10, which gives x-ray diffractograms of three types of physical mixtures of PVP-stabilized Pd, Pt, and Au monometallic nanoparticles, and the corresponding PVP-stabilized bimetallic nanoparticles (53). The diffraction patterns of the physical mixtures are consistent with the sum of two individual patterns, and are clearly different from those of the bimetallic nanoparticles, which have two broader peaks, indicating that several interatomic lengths exist in a single particle. By XRD one can easily understand if the obtained multi-metallic nanoparticles have an alloy structure or are simple physical mixtures of monometallic particles. 

As discussed, XRD has for many years been the standard, everyday characterization method for solid catalysts, and in almost every laboratory in this field there is access to an X-ray diffractometer. This instrument allows a wide variety of different characterizations, but there are also limitations of such equipment. For example, the limited resolution of an in-house diffractometer may often be insufficient for a detailed analysis. This point is illustrated in Fig. 5a, which shows the diffractogram of an industrial type steam-reforming catalyst consisting of nickel crystallites on a spinel support (35). The Ni(lll) and the spinel(400) lines overlap so that a detailed analysis is impossible. This problem can be overcome if the XRD... 

X ray diffractogram of SC-155 showed a big band centred at d = 4.07A assigned to the amorphous silica, and other two bands (d = 3.48 A and d = 2.07 A centred) assigned to carbon pseudo structure. (XRD bands are observed instead of peaks when amorphous phases or short order atomic arrangement are present). The AC-ref sample instead showed only two bands centred at the same values observed for the SC-155 carbon bands (3.48 and 2.07 A). 

The heavy corrosion layer on tablet P6 was analyzed using X-ray diffraction (XRD) in order to identify the products that had formed. The corrosion on P6 contained all the different types of corrosion observed on other tablets to date. Corrosion products were considered a possible reason fin- variation in the ICP-MS results, but not the TIMS results. XRD analysis bombards the sample with X-rays of one wavelength and determines the distance between atoms and atomic units in the sample. Diffraction of the X-rays occurs at different angles and intensities depending on the minerals in the sample. The diffractograms are compared to known standards to determine what minerals are present in the sample. 

A simple example of the use of XRD for quantitative phase analysis is as follows the phase composition of a perovskite was determined using the obtained XRD diffraction pattern. The x-ray diffractograms were obtained in a Siemens D5000 x-ray diffractometer, in a vertical setup 0-20 geometry in the range 15° < 20 < 75°, with a Cu Ka radiation source, Ni filter, and graphite monochromator [32],... 

X-Ray Diffraction. Diffractograms of the catalysts show that crystalline phases containing iron are formed upon calcination. In catalysts supported on rutile hematite (a-Fe202) is formed. When the iron phase is applied onto anatase, pseudo-brookite Fe2TiOs) is observed. The formation of pseudobrookite has previously been observed to take place only at 800°C for P-25 titania impregnated with iron solutions [71, but also at lower temperatures (550°C) when samples were prepared by co-precipitation or impregnation of freshly precipitated 100% anatase. In those samples, iron was in intimate contact with titania [8]. The results obtained with XRD indicate that iron is in intimate contact with the support indeed. 

X-ray diffraction. XRD patterns were acquired on a Philips PW1710 vertical goniometer using CuKa radiation selected by a graphite monochromator in the diffracted beam. All the samples were fully hydrated before XRD diffractograms were measured. Silicon powder was used as an internal standard. 

The representative low angle XRD diffractograms for TiOa coated glass fibers calcinated at 450 C, 500 C and 750 C for 1 hr after coating with 5 wt% Ti02 sol solution are shown in Figure 1. 

For XRD measurements the samples were ground in a WC/Co -mortar for one minute and homogenized manually in an agate mortar. X-ray diffractograms were collected with the Siemens D5000 diffractometer with 26 goniometer. The MoKa molybdenum anode X-ray tube was used at 30 kV and 40 mA with zirconium absorber. 

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