XRD Sample Preparation

After the sample is analyzed the XRD pattern is analyzed using available computer software to measure the interplanar d spacings, and corresponding line intensities. The X-ray pattern of the sample may be compared to reference samples stored in the computer for identification. Crystallite size is also determined using the Sherrer equation. 

Powder XRD has been applied extensively to the quantitative determination of a and p phase content of copper phthalocyanines as well as the p and y forms of 

Quinacridone Violet and Quinacridone Red. For quantitative analysis pure standards of each phase are mixed at various ratios from 0 to 90%. For the Copper Phthalocyanine blue a/P determination the 20 angles used are at 16.1° for the a form and at 18.1° and 18.5° for the P form. For the quinacridone p/y analysis the 20 angles are at 13.8° for the y and at 15.8° for the p form. 

Once the patterns are obtained the intensities of the Unes at the 20 angles corresponding to the phase of interest are measured. The ratio of intensities is then calculated at each concentration and plotted against the concentration of the phase to obtain a standard calibration curve. The regression equation of the Hne is used to calculate the phase content of unknowns. 

Using this approach quantitative analysis of the p or a form of copper phthalocyanine can be determined at levels below 3%. Similar detection limits have been obtained for the y and P forms of Quinacridone PV 19. 

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Table II. Summary of orienced mount (clay mineral) XRD sample preparation methods. 

Sample preparation methods vary widely. The very first procedure for characterizing any material simply is to look at it using a low-power stereomicroscope often, a material can be characterized or a problem solved at this stage. If examination at this level does not produce an answer, it usually si ests what needs to be done next go to higher magnification mount for FTIR, XRD, or EDS section isolate contaminants and so forth. 

Ceramics and minerals present many common problems, but ceramics warrant special treatment because elements of low atomic number predominate in them and they consequently offer x-ray emission spectrog-raphy of the light elements an excellent opportunity to prove its usefulness. Scott,8 in making this clear, emphasized the absorption and enhancement effects to be expected, and pointed out the need for careful sample preparation. By use of a General Electric XRD-5 spectrograph and associated equipment, he set up working curves for alumina, silica, potash, lime, phosphate, titania, and iron oxide in clays, refractories, and other ceramic materials. 

Fig. 1. XRD patterns of the sample prepared at 80 °C for (a) 10 min and (b) 40 min by the conventional and ultrasonic hydrothermal reduction method...

All the other characterization studies have been performed after the calcination step XRD experiments have shown that the material formed during the synthesis has the MFI structure Si and 27a1 MASNMR spectra indicated that this phase has a Si/Al ratio varying between 550 and 30 as a function of the sample prepared and also that no extra framework A1 is present. 

After the calcination step, experimental data (XRD, 29 i maSNMR) show that a zeolite with the silicalite structure has been formed. 29 i MASNMR indicates for the zeolite material a Si/Al ratio depending on the sample prepared it has been observed that both the natures of the silicon source and of the alumina supports may originate these fluctuations. 

In perovskite-type catalysts the formation of the final phase is completed already at 973 K. XRD and skeletal FTIR/FTFIR data for LalCol, LalMnl and LalFel calcined at 973 K evidence that only LalFel-973 is actually monophasic and consists of a perovskite-type phase with orthorombic structure. A perovskite type phase with hexagonal-rombohedral structure represents the main phase of LalCol-973, but traces of C03O4 and La2C05 are also present. In the case of LalMnl-973 two phases have been detected both with perovskite-type structure, one orthorombic and the other rombohedral. The calculated cell parameters of the dominant perovskite-type phase are reported in Table 1 for the three samples. The results compare well with those reported in the literature [JCPDS 37-1493, 32-484, 25-1060] which refer to similar samples prepared via solid state reartion. All the perovskite-type samples are markedly sintered... 

According to the characterizations by TEM and XRD, the sample prepared from a CH4/H2 plasma was composed of nanocrystalline diamond and disordered microcrystalline graphite. Then nondiamond carbon was effectively removed with an increase in [CO]. It is therefore concluded that the VDOS of the nanocrystalline diamond and DEC films extracted from the HREELS data is in qualitative agreement with the characterizations of TEM and XRD. Although the HREELS probes only the region near the surface, the agreement suggests that the surface dynamics do not differ dramatically from those of the bulk. 

XRD analyses were performed on oriented samples prepared by spreading of the sample suspension on a glass slide, followed by drying at room temperature. The XRD patterns were obtained with a PW 1130/00/60 Philips diffractometer using CuKa radiation (/, = 1,5405 A). Chemical analysis was carried out on a Perkin Elmer 3100 atomic absorption spectrometer after dissolution of the sample with several acids (HF, HCIO4, HC1) for 24h, and HN03 in a second time. 

Figure 1(a) compares the XRD spectra of both Beta sample the conventional one and that prepared from organofunctionalized seeds, showing their high crystallinity. However, for the sample prepared using the seed silanization treatment, the peaks are less intense and broader compared to those corresponding to the conventional zeolite, suggesting that the Beta (PHAPTMS) presents smaller crystalline domains. 

Fig. 7.4 XRD signal for powder samples prepared from bulk Si (top) and micro PS films produced on p-type electrodes using different anodization current densities, as indicated in...

The NiO phase could be reduced to metallic Ni by hydrogen treatment (723 K, 1 h). The crystallite size of Ni metal (estimated from XRD pattern of the reduced sample) is similar to that of the NiO in the unreduced sample (e.g., for 7B, the Ni metal crystallite size is 8.2 nm). The textural characterization studies reveal that for the samples prepared by coprecipitation + digestion and hydrothermal synthesis (methods B and C) the pore sizes are in the mesopore range (2.9 to 6.8 nm) (Table 11.2). 

X-rav Diffraction. XRD is the most common method used for coal mineralogy (6.7.8). Its major advantage is the ability to unequivocally identify many minerals. The main disadvantages are 1) reliance on reference minerals, 2) requires careful attention to sample preparation, and 3) low sensitivity to certain minerals (especially many clays) due to poor crystallinity and to particle orientation effects. Many laboratories analyze a separate concentrated clay... 

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... 

XRD patterns of the sample prepared mesoporous silica molecular sieves. 

Fig. 1 also shows the XRD patterns of the samples after hydrothermal treatment at 100°C for 4 days. It can be seen that samples prepared with additional TPA are quite stable to hydrothermal treatment. In contrast, the sample without TPA collapsed after such treatment. The nitrogen adsorption-desorption isotherms of calcined and hydrothermally treated MCM-... 

All samples prepared in this study showed XRD patterns atca. 20= 8°, 20°, 35°, 53° and 61° that are assigned to (001), (020, 110), (130, 200), (240, 310, 150) and (060, 330) diffraction peaks of smectite structure [6], The diffraction patterns derived from metal oxides (nickel, cobalt and zinc oxides) did not appear in XRD patterns of all samples after calcination at 873 K. 

A similar though considerably less well-ordered lamellar product is obtained when ethanol or methanol are used instead of water under solvothermal conditions Figure lb shows the powder XRD diagram of a sample prepared in ethanol at 90 °C dm = 3.50 nm). Considerably different products, however, are obtained when alcohols are used at lower temperatures, i.e. under non-solvothermal conditions. Figures lc and Id show the diffraction patterns of two example products from syntheses in methanol at 25 °C and in ethanol at 10 °C, respectively. In both cases the XRD reflections can be attributed to two distinct phases. One of these has a hexagonal symmetry with a dm value of 1.88 nm this mesophase will be discussed in detail below. An additional broad reflection is found at a Bragg angle comparable to that of the 001... 

Figure 2. XRD patterns for samples prepared using the same CTAB/Si02 ratio (0.45) and different H20/Si02 ratios as shown.

The mineralogical composition of all the samples included in the study was determined by XRD, using the same powdered sample prepared for XRF analysis. Measurements were performed using a PANalytical X Pert PRO alphal powder diffractometer (radius = 240 mm) using the Cu Ka radiation (A. = 1.5418 A), with a working power of 45 kV - 40 mA. The incident beam was passed through a 0.04 radians Soller slit, and the diffracted beam passed through a second slit. Moreover, the diffracted beam was Ni filtered. An X Celerator... 

Figure 10.4 shows a series of XRD patterns of samples prepared by glow... 

In assembly (b), reaction (10.2) is promoted and MWCNTs are converted to SiC. It is inferred that MWCNTs are changed to SiC nanorods by reaction (10.2) because the diffraction peaks of MWCNTs are not observed on XRD patterns of the sample prepared at 1550°C for 15 min. A small amount of nanometer-scale SiC granules are deposited by reaction (10.7) even in assembly (b). In this case, the MWCNTs are considered to play the role of carbon source. 

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