Debye-Scherrer

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... 

Data taken with a 143.2-mm diameter Debye-Scherrer camera using Cu Ka radiation (X 1.5418 A). 

In addition, an interesting, although negative, result has come from powder diffraction studies of the hexachloro compounds. We have examined Debye—Scherrer photographs of several samples known to contain predominantly hexachlorodibenzo-p-dioxins and have identified the patterns of at least three crystalline phases therein. (There are 10 possible isomers of hexachlorodibenzo-p-dioxin.) These patterns have been checked carefully against the calculated d-spacings and intensities of the 1,2,3,7,8,9-hexa isomer described by Cantrell, Webb, and Mabis (I) and also against an observed pattern supplied by Cantrell and believed to be from the low temperature phase of the same material. Yet to date we... 

Figure 1 is a TEM photograph of the Cu (10wt%)/Al2O3 catalyst prepared by water-alcohol method, showing the dispersed state of copper and was confirmed the particle sizes from XRD data. Figure 2 is X-ray diffraction patterns of above-mention catalysts, was used to obtain information about phases and the particle size of prepared catalysts. Metal oxide is the active species in this reaction. Particle sizes were determined fix)m the width of the XRD peaks by the Debye-Scherrer equation. 

FIGURE 27.2 Debye-Scherrer powder method. Cones of reflected and transmitted radiation are produced. In this example the pattern is recorded with photographic film. Alternatively,... 

For isotropic materials all reflections represent concentric rings (Debye-Scherrer rings) in an image recorded on 2D detector5 if during exposure the detector was... 

The X-ray powder diffraction pattern of sodium valproate was determined by visual observation of a film obtained with a 143 2 mm Debye-Scherrer Powder Camera (Table IV). An Enraf-Nonius Difractis 601 Generator 38 KV and 18 MA with nikel filtered copper radiation A = 1.5418, was employed (4). 

Figure 5.8 A Debye-Scherrer powder camera for X-ray diffraction. The camera (a) consists of a long strip of photographic film fitted inside a disk. The sample (usually contained within a quartz capillary tube) is mounted vertically at the center of the camera and rotated slowly around its vertical axis. X-rays enter from the left, are scattered by the sample, and the undeflected part of the beam exits at the right. After about 24 hours the film is removed (b), and, following development, shows the diffraction pattern as a series of pairs of dark lines, symmetric about the exit slit. The diffraction angle (20) is measured from the film, and used to calculate the d spacings of the crystal from Bragg s law.

Considering the fact that the X-ray diffraction pattern of a crystal depends on its lattice structure, pigment powders can be analyzed with a Debye-Scherrer diffraction camera to establish a correlation between X-ray diffraction and crystal modification. It is synthetically not possible to produce a defined crystal modification of a new pigment. Attempts to modify the preparative procedure or to apply different aftertreatment may result in a pigment of two or more crystalline forms, different not only in lattice structure, but also in color and performance. 

Nitka, H. Debye-ScHERRER-Aufnahmen an Germanium zwischen 20° absolut und 1110° absolut. Physik. Z. 38, 896 (1937). 

Owen et al. reported x-ray powder diffraction data for procaine and 16 other anesthetics, as obtained using the Debye-Scherrer technique [55]. 

Chemical composition of fresh HTs was determined in a Perkin Elmer Mod. OPTIMA 3200 Dual Vision by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline structure of the solids was studied by X-ray diffraction (XRD) using a Siemens D-500 diffractometer equipped with a CuKa radiation source. The average crystal sizes were calculated from the (003) and (110) reflections employing the Debye-Scherrer equation. Textural properties of calcined HTs (at 500°C/4h) were analyzed by N2 adsorption-desorption isotherms on an AUTOSORB-I, prior to analysis the samples were outgassed in vacuum (10 Torr) at 300°C for 5 h. The specific surface areas were calculated by using the Brunauer-... 

FIGURE 2.4 (a) Cones produced by a powder diffraction experiment (b) experimental arrangement for a Debye-Scherrer photograph. 

The Debye-Scherrer formula enables the thickness of a crystallite to be calculated from the peak widths ... 

X-Ray Powder Patterns. Samples for x-ray pattern determinations were sealed in 0.2-mm. glass capillary tubes under an atmosphere of argon. The samples were then exposed to nickel-filtered, CuKa radiation in an 11.459-cm. Debye-Scherrer camera for 18 to 20 hours. 

The preceding setup allows both X-ray diffraction (32) and absorption experiments (33, 34). The capillary geometry was used until about 30 years ago for ex situ XRD studies in connection with the placement of Lindemann tubes in powder Debye-Scherrer cameras. At that time, films were used to detect the diffracted X-rays. Today, this cumbersome technique has been almost completely replaced as modern detectors are used. 

The film is in contact with the cylindrical brass frame of the camera and is held in position by springs 8. Sharp edges E terminate the exposed part of the film abruptly. Light is excluded by a brass cover which fits over the whole camera the X-rav beam is admitted through a hole covered with black paper. Further details of the construction and use of Debye- Scherrer powder cameras can be found in a paper by... 

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