XRD diffractograms

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]).

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. 

Figure 1. Powder XRD diffractograms for the oxide for materials containing up to 10% MCM-41 with different vanadium contents vanadium content. There is a slight shift...

The process of Ni migration may also have contributed to the observed modification of the XRD diffractogram of the samples (Figs. 5a and 5b). The difi actograms of the spent catalysts are characteristic of the H-form of ZSM-5 [12],... 

None of the copper-containing samples showed in their XRD diffractograms peaks which may be ascribed to Cu-containing phases. xCA or CuxCA (x=10, 39) samples showed features due to the CeOj and 7-AI2O3 phases, with broad peaks due to the smdl crystallite size. Somewhat narrower CeOj peaks were detected upon increasing ceria content of these samples. Only peaks due to the Ce02 structure were observed for the CuC catalyst. 

XRD diffractograms of fresh, severely coked and lightly coked catalysts... 

Fig. 2 XRD diffractograms of clay treated with an aliphatic amine (a) and those recorded on nanocomposites containing it at 1 vol% (b) and 5 vol% (c)...

The main disadvantage is that single crystals are not produced in these type of reactions. However, powder X-ray diffraction (also known as XRD) can be used to solve this problem, either by direct solution of the structure from the XRD-data, (sometimes possible although not quite a standard method) or by comparison to the XRD diffractogram of a known structure. If the product is a new compound it may be possible to grow single crystals from seeds using the powder material and in that way get the X-ray structure [58]. 

Generally, the structure of nanocomposites has typically been established using XRD and transmission electron microscopy (TEM) observation. The XRD diffractograms and related TEM images produced by different types of hybrid are illustrated in Fig. 4 [21]. 

Figure 1.7 shows an XRD diffractogram 20/co scan from an instrument under Bragg Brentano configuration using Cu radiation. The sample was a powder prepared from a rock obtained near the Michigan Lake. The basic general interpretation of that type of data is as follows ... 

The exchanges with and Cs" from NaY lead to a decrease of the surface areas and micropore volumes (Table 1) for HY and CsY and also to a decrease of the intensities in the XRD diffractograms (Fig. 1). For HY, the dealumination process which occurs in the protonated zeolites may lead to a partial breakdown of the lattiee. For CsY, Cs cation is bigger than Na and the exchange is rather difficult [6]. Therefore, several exchanges are needed and as the sample is heated many times, a partial breakdown of the zeolites could occur. The HY and CsY samples thus contain a certain amount of amorphous material of which the adsorptive properties are not known. The proportion of amorphous material may be estimated from the specific surface area ratio considering the NaY sample as the reference. This approximation leads to a proportion of amorphous material equal to 25.1% for HY and to... 

Figure 1 XRD diffractograms for NaY, HY and CsY 3. ADSORPTION STUDY 3.1 The Pulse Chromatographic Method...

Incidentally, these zeolites have been identified from the XRD diffractograms of the samples, as presented in Table 5.38. The mineralogical phase transition in the activated residues also reveals the higher zeolitization characteristics of the OHA for synthesizing a class of zeolites with a slightly higher SAR value (2.64 > SAR > 1.60), which is in close proximity to common fly ash zeolites, Faujasite and Analcime [47]. 

In comparison to XRD diffractogram of the fly ash (refer Fig. 6.35a), such shift in the prominent peaks is noticeable from 20 = 27.01 to 29.68, each of which conform to two different grades of zeolite X (viz., Na-X and Na-Y). This could be an indication of decrease in d-spacing and hence, increased atomic packing in the zeolite X due to reactivation during second and third steps of fusion, corresponding to NaOH/RFA ranging from 1.0 to 1.4. 

XRD diffractogram of foamed PCL and the Gaussian fit used to approximate the amount of the amorphous region in the sample. 

XRD Diffractograms were recorded on a SIEMENS D5000 diffractometer. Phases were identified with referenee to the JCPDS database. 

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