Diffraction XRD

Fig. 3. (a) XRD diffraction patterns and (b) PL sprettum of the GaN nano-structures grown on (0001) AI2O3 substrate using Ga(mDTC)j pimssor. 

Fig. 23 XRD diffraction patterns in the lateral and vertical directions in the image plate study of a stearate/LDH cast film. Reprinted with permission from [151]. Copyright American Chemical Society...

Hydrolysis of Alkoxides - A different thermal evolution of the precursor phase was observed for a BaAli20i9 sample prepared via hydrolysis of alkoxides.8,9 For this sample no XRD diffraction lines were detected after heating at 1000°C. At 1200°C Ba-hexaaluminate formed, and it was the only phase detected in the XRD spectra. Calcination at 1450 °C resulted in higher sharpness and intensity of the XRD reflection of Ba-hexaaluminate. No further changes were observed upon calcination at 1600°C. Also in this case, the appearance of Ba-(3-Al203 was accompanied by a marked drop of surface area. However, the... 

The x-//J-Si3N4 ratio is measured by X-ray diffraction [228-231]. In earlier investigations only some peaks where chosen [229-231]. New techniques based on the Rietveld method use the whole angle range of the XRD diffraction pattern [219,228]. This results in more accurate data even in textured samples [228], The amount of amorphous Si3N4 also can be analysed by this method using an internal standard [224]. 

The angle 0h is the angle between the X-ray polarization direction, s, and the direction to the atom h in the j shell. For isotropic materials, like powders, the sum becomes N/3. For thin films like heteroepitaxial metallic films [19], there is often an intrinsic asymmetry leading to different in-plane and out-of-plane bonds. Otherwise, the polarization dependence of EXAFS can be also an important tool for studying texturized films providing an alternative probe to the long range order technique such as diffraction when XRD diffraction is dominated by that from the substrate. 

The XRD diffraction patterns of the shoe (suspect) and riverbank (control) soil samples closely match each other—a technique that can be likened to fingerprint comparisons (Figure 1.3). However, what is the significance of this close match If the two soil samples, for example, contain only one... 

Upon annealing at 145 °C, the NanoPQT thin film gives an XRD diffraction pattern (Fig. 4.9d) which is similar to that from an annealed thin film from the hot solution (Fig. 4.6d). The interchain distance tightens to 17.2 A (28 = 5.T), accompanied by the disappearance of 28 = 7.4° and 22.1° diffraction peaks associated with the side-chain interlayer and n-n stacking respectively. The disappearance of these diffraction peaks is indicative of the preferential orientation of PQT-12 lamellar structures with their (100) axes normal to the substrate - a result of the interaction of PQT-12 dodecyl side-chains with the octyl chains of the OTS-8 modified surface induced and facilitated by thermal annealing. 

All the substituted indolo[3,2-b]carbazoles (5) with long alkyl side-chains form highly crystalline thin films on vacuum deposition. The X-ray diffraction patterns of the thin films, deposited at respective optimum substrate temperatures, give sharp and intense crystalline diffraction peaks (Fig. 4.13). Table 4.2 summarizes the XRD data and extracted interlayer distances of molecular orders of indolo[3,2-h]carbazoles in crystalline thin films. Only 5e, which has no long alkyl chain, has broad XRD diffraction peaks indicative of its amorphous nature. These results... 

Sn(II) and Nb(V) species changed their coordinations with the liquid composition. Nb-Sn alloy samples were prepared by the potentiostatic method and analyzed. The results showed that the Nb content in the alloy could be increased by increasing the bath temperature to 160 °C and increasing the NbCh content in the bath. However, increasing the NbCls mole fraction in the bath also increased the viscosity of the bath. Pulse electrolysis was found to be effective in increasing the Nb content in the alloy. The maximum Nb content in the alloy was 60.8 wt% from constant potential electrolysis and 69.1 wt% from pulse electrolysis. XRD diffraction patterns showed that the electrodeposits contained crystalline Sn and NbsSn which is a superconductor material. 

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],... 

Figure 4.4 [32] shows the XRD diffraction pattern of the BaCe0 95Yb005O3 5 perovskite. It is evident, by comparing the obtained pattern with the powder diffraction data contained in the... 

Oda et al. observed that the spots of the diffraction patterns of AP-CVD ZnO films grown with DEZ and alcohols become sharper as the thickness of the ZnO film increases [14]. This is a further indication that the crystallites become larger as the thickness of the ZnO films is increased (in this case, also, only the (0002) peaks are visible in the XRD diffraction pattern). LP-CVD ZnO The evolution of the structural properties of LP-CVD ZnO thin films with their thickness has been comprehensively investigated in [17] and is presented in detail hereafter. 

B2.2 SiC substrates for growth of GaN and related compounds TABLE 1 Summary of XRD diffraction measurements of GaN films grown on 6H-SiC. 

The as-prepared ZSM-48 was calcined in air at 500°C for 48 hrs to give H,Na-ZSM-48. This was washed with 1.0 M HC1 at 25°C for 3 hrs to give H-ZSM-48. The material was then heated at 450°C for 30 hrs in a tubular quartz furnace (Hamdan, H. Sulikowski, B. Klinowski, J. T. Phvs. Chem.. in press) with water being injected at a rate of 12 ml per hour into the tube by a peristaltic pump so that the partial pressure of H2O above the sample was 1 atmosphere. It was then exchanged with 1 M NH4NO3 and steamed at 650°C for a further 16 hrs. The ammonium exchange was repeated and the zeolite steamed at 650°C for 16 hrs and at 800°C for 8 hrs. XRD diffraction patterns (not shown) did not indicate any loss of crystallinity upon thermal treatment. 

Several beta-zeolite samples have been used as catalysts (A,B,C). All of them show the XRD-diffraction pattern of beta-zeolite. However, it is an astonishing result that all of them showed excellent selectivities (> 92%) while the conversion varied from 40 to 90% (Fig. 15.7). 

The X-ray powder diffraction patterns (XRD) were obtained on a Rigaku D/Max 2500 diffractometer fitted with a fine-focus copper X-ray tube and operated at lOOkV and 40mA, respectively. The relative crystallization intensity (RCI) of CAS-1 was calculated following the procedures the five XRD diffraction peaks of the sample... 

Figure 7a shows the powder XRD pattern of the as-prepared mesostructured titania from titanium butoxide. The mesostructure was collapsed at 400 °C for 5 h, indicated by powder XRD diffraction and adsorption properties. 

Interestingly, Pt°-(His) nanoclusters prepared by standard NaBH4 reduction from precursor complexes of Pt (II) and histidine in aqueous solutions produced nanoclusters with a plasmon resonance at 270 nm as compared to a theoretical maximum plasmon band predicted at 345 nm for particles <20 nm. A high degree of crystallinity was confirmed by the (100), (200), (220), and (020) diffractions in the powder XRD diffraction peaks. TEM analysis demonstrated a tight distribution of particles with an average diameter of 3.4 l.Onm.i... 

We were interested in the potential of the syndiesized diblock copolymers as templates in the synthesis of mesostructured silicate materials. Our focus was the pr aration of mesoordered thin films via the evaporation-induced self-assembly process [7]. For this purpose PDMS-b-PEO were mixed with a precursor solution containing the network-building species, and films were produced via a dip-coating procedure [8]. XRD diffraction patterns confirmed the formation of lamellar materials which were stable upon calcination at 430 °C/3 h. 

The XRD diffraction patterns of the zeolites impregnated with copper(II) chloride were identical to that of the parent materials. This shows that no copper chloride clusters had been formed with diameters above 2.5 nm, the minimum detectable size [11]. 

From the above results we can propose the following mechanism for hexagonal MCM-41 synthesis. At low crystallization temperature or short crystallization time a fibrous agglomerate structure is often observed by SEM on intermediate samples. The 100 and 200 reflections are not detected by XRD and the value of the specific surface area is low. This reflects the initial step of synthesis which is generally referred to the nucleation step in zeolite synthesis. After this step, the 100 and 200 reflections are present on the XRD diffraction pattern. The value of the specific surface area is between 700 and 900 m /g. The fibrous agglomerate structure disappears and crystals of MCM-41 appear. This corresponds to the crystallization step. Finally if both the synthesis temperature and time are continuously raised, a triphasic mixture MCM-41, MCM-50 and amorphous phase is identified by XRD. The... 

Figure 1. Schematic of an experimental setnp for high-pressure X-ray diffraction (XRD) experiments on nanocrystals nnder pressure of tens of GPa (1 GigaPascal s 10,000 atmospheres). Nanociystal powder is dissolved in a pressme medinm and placed between two opposing diamonds, which are clear to X-rays and visible absorption. The pressme is applied by bringing the diamond closer together, and measmed nsing pieces of ruby chips placed inside the pressme cell. The XRD diffraction peaks are Debye-Scherrer broadened by the finite size of the particles, yielding information on the shape and size of the nanocrystals before and after the transition, snch as shown in Figure 3.

The characterization of an amorphous material is difficult because it lacks characteristic XRD diffractions, so that Auger or Mossbauer spectroscopies are preferred, along with other conventional analytical assays such as spot test and iodo-metric titration [71]. The Fe203 nanoparticles are converted to crystalline Fe304 nanoparticles when heated to 420 °C under vacuum or when heated to the same temperature under a nitrogen atmosphere. The magnetization of pure amorphous Fe203 at room temperature is very low (< 1.5 emu g ) and it crystallizes at 268 °C. 

Crystalline structures of oxides and nitrides were analyzed by X-ray diffraction (XRD). Diffraction patterns were collected using a Rigaku DMAX-II diffractometer with CuKa radiation. Structural and compositional changes of the CoMo nitrides were observed by SEM (Philips, 535M) and elemental analysis (Elementar Analysensystem. GmbH Vario EL). Smface areas of the samples were measured by N2 adsorption at 196°C. 

Because of the large unit cell, the XRD diffraction peaks appear at very low angles of 28. Some problems for structural analysis of mesoporous materials by powder XRD are the lack of enough diffraction peaks, overlapping of the peaks, and loss of structure-factor phase information. Since most samples have the low crystalline quality, the calibration of equipment is very important. The normal standards for calibrating a diffractometer (e.g., Si, quartz) are not very efficient, so standards for low-angle calibration should be used (e.g., lead stearate). 

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