Debye-Scherrer X-ray diffraction

The films were deposited onto NaCl or KBr discs to facilitate examination by infrared transmission. Substrates of platinum, aluminum, ALOn, and fused SiO approximately one cm. in diameter were prepared for the rate studies. The index of refraction and isotropic character of film specimens obtained from the substrates and/or gas inlet tube were determined with a petrographic microscope. Debye-Scherrer x-ray diffraction powder patterns were made to establish whether the films were amorphous or crystalline. 

The quality of the samples was checked by scanning electron microscopy (ISl 100), Debye-Scherrer X-ray diffraction and nitrogen physisorption at 77 K. 

K. A slurry (16 g) of NaX seeds (5 g) is added following to the gel formation, i.e. after ca. 15 min, under heavy stirring. The formation of the NaY crystals is finished after one week. The quality of the charge is checked by scanning electron microscopy, Debye-Scherrer X-ray diffraction, nitrogen physisorption at 77 K and reversible water uptake. 

Formation of C8K from Metaanthracite Coal. This relatively simple chemistry can also cause intercalation of nongraphitic, but benzenoid, carbonaceous solids. Figure 4 presents a Debye-Scherrer X-ray diffraction photograph of a polycrystalline C8K compound formed by the insertion of potassium metal at 110 °C into a metaanthracite from Newport County, RI (27). A sketch of this photograph is also shown in Figure 4. The initial crystallite size along the c axis, the direction of stacking, was 124 A, as measured from the line width of the (002) line at d = 3.36 A. The most... 

Figure 4. Debye-Scherrer X-ray diffraction photograph of C8K made from metaanthracite coal and potassium metal (top), and sketch of this photograph...

While much of his reputation was based on nonpolymeric accompHshments, such as demonstrated by the Debye-Huckel theory, the Debye-Scherrer x-ray diffraction technique, the Debye-Sears effect in liquids, the Debye temperature, the Debye shielding distance, the Debye frequency and the Debye unit of electric moment, his development of the hght scattering technique for the determination of the molecular weight of polymers resulted in his also being recognized as a world class polymer scientist. 

Fig. 6 (a) Observed Debye-Scherrer X-ray powder diffraction patterns (Cu-Ka) of the nestled C,4AsF6, (6) quartz capillary background, (c) calculated (10/) diffuse scattering, (d) simulated pattern with (00/) and (11/) crystal reflections, and (10/) diffuse scattering... 

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. 

XRD on battery materials can be classified as powder dififaction, a technique developed by Peter Debye and Paul Scherrer. In powder dififaction the material consists of microscopic crystals oriented at random in all directions. If one passes a monochromatic beam of X-rays through a fiat thin powder electrode, a fraction of the particles will be oriented to satisfy the Bragg relation for a given set of planes. Another group will be oriented so that the Bragg relationship is satisfied for another set of planes, and so on. In this method, cones of reflected and transmitted radiation are produced (Fig. 27.2). X-ray diffraction patterns can be recorded by intercepting a... 

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. 

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-... 

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. 

University in Ithaca. Nobel Prize in 1936 for contributions to the knowledge of molecular structure based on his research on dipole moments, X-ray diffraction (Debye-Scherrer method), and electrons in gases. His investigations of the interaction between ions and electric fields resulted in the - Debye-Huckel theory. See also -> Debye-Falkenhagen effect, - Debye-Huckel limiting law, - Debye-Huckel length, - Debye relaxation time. 

The deformation of the lattice as a result of the mechanical working is seen from the broadening of the lines in the X-ray diffraction picture, which are narrow under normal circumstances (Debye-Scherrer or powder diagram). 

Powder X-ray diffraction (XRD) is performed on a Siemens D5005 diffractometer with Cu Ka radiation. The particle size is calculated from the X-Ray line broadening, using the Debye-Scherrer equation. DRS is measured by Perkin-Elmer Lambda 20 UV-visible spectophotometer at room temperature in the wavelength region between 200 and 800 nm. Raman spectra are recorded on a Broker RFS 100 with 2 cm resolution. 

Shortly after the discovery of X-ray diffraction by von Laue and von Knipping in 1910, Debye and Scherrer (1916) in Germany and HulP (1917) in the United States independently pioneered X-ray powder diffraction. Zachariasen " (1949) determined the first structures solely from powder diffraction data by using an intuition-based trial-and-error approach. The structures of UCI3 as well as a- and /S-UFs were solved this way. More than a decade later Zachari-asen and Ellinger (1963) used direct method procedures to... 

The x-ray diffraction patterns were obtained by mounting the sample particles on a glass filament in a 114.59-mm diameter powder camera (Debye-Scherrer) and irradiating with Cu-Ka x-rays at 30 kV and 15 mA for periods of time ranging from 8 to 24 h. 

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 structural transition is directly monitored using X-ray diffraction (XRD) (see Fig. 1), by observing the disappearance and appearance of the characteristic peaks. The limits of this method are mainly from the small sample size of -100 microns from a solution of a few nanoliters, compressed between two diamonds of l-mm thickness. The small physical size of the nanocrystal produces Debye-Scherrer broadening of the diffraction peaks (Cullity 1956), and very concentrated samples are required (optical... 

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