X-ray powder diffraction photographs

X-Ray powder diffraction photographs suggest that NbSCl3 and TaSCl3 are isostructural (13). 

The X-ray powder diffraction photographs show that the salts AgFSbF6 and AgFBiF6 are isostructural with one another but not with the other known AgFMF6 structures. The structure is not known. 

Of course several formulations are possible for the compound. Fortuntely the solid gave a simple X-ray powder diffraction photograph which was indexed on the basis of a cubic unit cell, a = 10.032A. The compound was apparently structurally similar to potassium hexafluoro-antimonate (V) the structure of which had been given by Bode and Voss Furthermore we found that nitro-syl hexafluoro-osmate (V) and nitrosyl hexafluoro-anti-monate (V) were also isomorphous with the compound. Figure 4 shows the close resemblance of the X-ray powder... 

X-ray powder diffraction photographs. The quartz capillaries used for X-ray powder diffraction studies were dried under vacuum (10 Torr) at 1070 K for 24 h before being transferred to the dry Ar atmosphere of a Vacuum Atmospheres Corporation DRILAB. X-ray powder samples were prepared as previously described (17). Photographs were taken using a 45-cm-circumference G.E. camera with Straumanis loading, the radiation being CuKa with a nickel filter. 

X-ray Powder Diffraction Photographs (XRDP) were obtained using Ni-filtered Cu Ka radiation using General Electric Co. Precision Cameras (circumference 45 cm, Straumanis loading). 

X-ray Powder Diffraction. Photographs were taken on products in quartz capillaries using Debye-Scherrer cameras. 

Another technique, more time-consuming but chemically not so aggressive as the acid treatment, is to dissolve the tin in benzene containing 10% iodine. After the procedure, the solid product may be coated with a very thin amorphous brownish product of unknown composition. The coating material does not give any extra lines in the X-ray powder diffraction photographs, however. 

X-Ray Investigations. X-ray powder diffraction photographs (Ievins-Straumanis mounting) were taken of samples as initially prepared and after heating. Some Guinier photographs were also obtained. Visual comparisons of line intensities were made. 

Figure 6. Generalized X-ray Powder Diffraction Photograph for a Smectic Sample. 

X-ray powder diffraction studies are perfonned both with films and with counter diffractometers. The powder photograph was developed by P Debye and P Scherrer and, independently, by A W Hull. The Debye-Scherrer camera has a cylindrical specimen surrounded by a cylindrical film. In another commonly used powder... 

The X-ray powder diffraction pattern of parbendazole has been measured using a Philips PW-1050 diffractometer, equipped with a single-channel analyzer and using copper Ka radiation. The pattern obtained is shown in Fig. 5.1, and the data of scattering angle (° 26) and the relative intensities (f/7max) are presented in Table 5.1 (as photographic and diffractometric pattern data) as an attempt to establish a reference chart for the purpose of identification of parbendazole. 

The crystal used for data coUection was transferred to an Enraf-Nonius CAD-4 diffractometer. Automatic peak search and indexing procedures yielded the same monoclinic cell as derived from the X-ray powder diffraction data and precession photographs. Testing showed that the cell was indeed primitive and that there was no superlattice present. Table 5 gives the crystal data and X-ray experimental parameters, and Table 6, the interatomic distances and angles. Positional and thermal parameters are given in Table S3 (Supporting Information)... 

Area detectors record diffraction pattern in two dimensions simultaneously. Not counting the photographic film, two t)q)es of electronic area detectors have been advanced to a commercial status, and are becoming more frequently used in modem x-ray powder diffraction analysis. 

Typical x-ray powder diffraction data for the phosphorus-substituted zeolites are given in Tables II and III. Unit cell dimensions have been determined for several of the phosphate zeolites and compared with the structurally related phosphorus-free zeolites. The unit cell dimension of cubic P-C zeolite (13.2 wt % P2O5) was found to be 13.75 A from singlecrystal precession x-ray photographs. A single crystal of the analogous zeolite C has an a = 13.73 A. The crystal structure of zeolite P-C (13.2 wt % P2O5) has been determined by Birle et ah and will be reported elsewhere (3). 

Both chondrosamine and D-glucosamine are usually isolated as hydrochlorides but rotational and mutarotational differences between these derivatives are not sufficiently sharp to distinguish between them. The x-ray diffraction pattern is quite distinct for each and the x-ray powder photograph method21 would appear to be the best for identifying small amounts. 

Probably the most widely employed technique now used in phase studies is powder X-ray diffraction. The X-ray powder pattern of a compound can be used as a fingerprint, and data for many compounds are available. This can be illustrated with reference to the sodium fluoride (NaF)-zinc fluoride (ZnF2) system. Suppose that pure NaF is mixed with a few percent of pure ZnF2 and the mixture heated at about 600°C until reaction is complete. An X-ray powder photograph will show the presence of two compounds (or phases), NaF, which will be the major component, and a small amount of a new compound (point A, Fig. 4.1a). A repetition of the experiment, with gradually increasing amounts of ZnF2 will yield a similar result, but the amount of the new phase will increase relative to the amount of NaF until... 

Chapter V, on identification by X-ray methods, is concerned with the practical details of taking X-ray powder photographs, and also includes elementary diffraction theory, taken as far as is necessary for most identification problems. 

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