Aluminum diffraction pattern

Several nonequilihrium forms of aluminum oxides have been observed (11,12) in hydrothermal experiments at low water vapor pressures in the temperature region of 300—500°C. The KI—AI2O2 form, also known as tondite [12043-15-1] AI2O2 I/5H2O, is characterized by a distinct x-ray diffraction pattern. 

Clays are composed of extremely fine particles of clay minerals which are layer-type aluminum siUcates containing stmctural hydroxyl groups. In some clays, iron or magnesium substitutes for aluminum in the lattice, and alkahes and alkaline earths may be essential constituents in others. Clays may also contain varying amounts of nonclay minerals such as quart2 [14808-60-7] calcite [13397-26-7] feldspar [68476-25-5] and pyrite [1309-36-0]. Clay particles generally give well-defined x-ray diffraction patterns from which the mineral composition can readily be deterrnined. 

Mica [12001 -26-2]—Cl Pigment White 20, Cl No. 77019. A white powder obtained from the naturally occurring mineral muscovite mica, consisting predominantly of a potassium aluminum siHcate, [1327-44-2] H2KAl2(Si0 2- Mica may be identified and semiquantitatively determined by its characteristic x-ray diffraction pattern and by its optical properties. 

From shock compression of LiF to 13 GPa [68] these results demonstrate that X-ray diffraction can be applied to the study of shock-compressed solids, since diffraction effects can be observed. The fact that diffraction takes place at all implies that crystalline order can exist behind the shock front and the required readjustment to the shocked lattice configuration takes place on a time scale less than 20 ns. Another important experimental result is that the location of (200) reflection implies that the compression is isotropic i.e., shock compression moves atoms closer together in all directions, not just in the direction of shock propoagation. Similar conclusions are reached for shock-compressed single crystals of LiF, aluminum, and graphite [70]. Application of these experimental techniques to pyrolytic BN [71] result in a diffraction pattern (during compression) like that of wurtzite. 

Figure 14-15 shows three X-ray diffraction patterns obtained from small crystalline particles of metallic copper, aluminum, and sodium. The qualitative similarity of the patterns given by copper and aluminum shows that they have the same crystal packing. Careful measurements of the spacing of the lines indicate that the atoms... 

Fig. 14-15. X-Ray diffraction patterns of finely divided metallic copper, aluminum, and...

Since the first structure determination by Wadsley [56] in 1952 there has been confusion about the correct cell dimensions and symmetry of natural as well of synthetic lithiophorite. Wadsley determined a monoclinic cell (for details see Table 3) with a disordered distribution of the lithium and aluminium atoms at their respective sites. Giovanoli et al. [75] found, in a sample of synthetic lithiophorite, that the unique monoclinic b-axis of Wadsley s cell setting has to tripled for correct indexing of the electron diffraction patterns. Additionally, they concluded that the lithium and aluminum atoms occupy different sites and show an ordered arrangement within the layers. Thus, the resulting formula given by Giovanelli et al. 

In addition to the ICDD, publications dealing solely with the powder patterns of drugs appear occasionally [12-15], In 1971, Sadik et al. pointed out that the identification test for kaolin (in NF XIII) was a test for the presence of aluminum, and therefore both kaolin and bentonite gave positive results [16]. Since the two compounds have different crystal structures, their x-ray diffraction patterns are different, and therefore XPD was recommended for identification of these compounds. In the current edition of USP, the identification of bentonite is based on its powder x-ray pattern [3]. 

The interaction of oxygen with Cu(100) contrasts (75) very obviously with the behavior observed with lead 60,60a) and aluminum (70). At 80 K the 0(1 s) peak after 20 L exposure to oxygen is centered at 530.5 eV, the FWHM value is exceptionally large ( 4.5 eV), and there is only weak ordering within the 2x2 adlayer as reflected by LEED. After 300 L exposure the diffraction pattern exhibits y/2 x. 2)7 45° symmetry, and the 0(ls) peak is now centered at 531.7 eV. 

The aluminum content of the as-synthesized zeolites also influences their X-ray powder diffraction pattern. The height of the main peak in the patterns decreases with decreasing Si/Al ratio in the zeolite, but their width increases simultaneously so that the area remains practically constant for all samples. On the other hand, the dhki distance corresponding to the diffraction peak at 43 of 20 correlated linearly with the aluminum content of the zeolite (Figure 4). However, the lack of knowledge of the crystal structure of Beta zeolite makes it impossible to correlate the Al content and unit cell parameters. 

X-ray diffraction patterns of powdered catalysts were recorded with a Rigaku RINT 1200 diffractometer using a radiation of Ni-filtered Cu-Ka. BET surface area and pore size distribution were calculated from the adsorption isotherm of N2 at 77 K. The BJH method was used for the latter. Aluminum content was determined by ICP spectrometer. FTIR spectra of adsorbed NH3 were recorded with a JASCO FT/IR-300 spectrometer. The self-supporting wafer was evacuated at prescribed temperatures, and 25 Torr of NH3 was loaded at 473 K. After NH3 was allowed to equilibrate with the wafer for 30 min, non-adsorbed NH3 was evacuated and a spectrum was collected at 473 K. The differential heat of adsorption of NH3 was measured with a Tokyo-riko HTC-450. The catalyst was pretreated in the presence of 100 Torr oxygen and evacuated at 873 K. The measurements were run at 473 K. 

Below, left Diffraction pattern from an aluminum-manganese alloy showing apparent tenfold symmetry. From C. Janot, Quasicrystals, A Primer, 2nd ed. (London Oxford Univ. Press, 1994), p. 102, top photo (a). 

An electron diffraction pattern of the aluminum-manganese alloy and a computed Fourier pattern of a three-dimensional Penrose tiling are shown in Figure 2.11. 

The x-ray powder diffraction pattern of etodolac was obtained using a Rigaku MiniFlex powder diffraction system, equipped with a horizontal goniometer in the 0 /2-0 mode. The x-ray source was nickel-filtered K-a emission of copper (1.544056 A). A 10-mg sample was packed into an aluminum holder using a back-fill procedure, and was scanned over the range of 50 to 6 degrees 2-0, at a scan rate of 0.5 degrees 2-0/min. 

X-ray powder diffraction pattern of racemic mandelic acid (Aldrich lot KN07114MT). The aluminum calibration peak from the cell holder is marked. 

FIGURE 14 X-Ray diffraction patterns of crystalline and amorphous forms of aluminum oxide. Pattern A is the highly crystalline Qf-Al203 formed at high temperatures from B, the amorphous y-AI203 phase. 

All of the hydrotaleite-derived magnesia supports were prepared by first coprecipitating magnesium aluminum hydroxycarbonate in the presence of Mg and Al nitrates, KOH, and K2C03 according to procedures already described (8,9). Hydrotaleites were then decomposed by calcination at 873 K for 12-15 h to yield the binary oxide to be used for a catalyst support. The specific surface area of the hydrotaleites determined by nitrogen adsorption was typically about 220 m2g 1 after calcination. X-ray powder diffraction patterns of the materials were recorded on a Scintag X-ray diffractometer. 

Our support precursor having a Mg Al molar ratio of about 3 1 shows an x-ray diffraction pattern typical of hydrotalcite (see Figure la) (10). After calcination at 873 K the resulting diffraction pattern exhibits diffuse peaks corresponding to MgO (Figure lb). No evidence for separate crystalline aluminum phases was found so A1 cations probably remain closely associated with or dissolved in the MgO structure. However, it is possible that amorphous alumina phases, not detectable by x-ray diffraction, may be present in our mixed oxide. 

Aluminum iodide is dimeric in both the solid and gaseous states and in solution. The melting point of the product prepared as described above depends upon the technique employed. Samples contained in pyrex capillary tubes sealed with soft wax begin to decompose at 179° melting is complete and a meniscus is formed at 189.9° (corr.). In sealed capillaries, decomposition is first detectable at 178 to 179°, and melting is complete at 184° (corr.). Aluminum iodide is best characterized by its x-ray-diffraction pattern, which includes five quite distinct max-... 

Figure 12.11 shows the XRD patterns of a nanocrystalline Al film obtained at a constant potential of —1.7V for 2h at 100°C in the ionic liquid [Pyip] TFSA containing 1.6 M AICI3 on a glassy carbon substrate. The XRD patterns show the characteristic diffraction patterns of crystalline Al, furthermore the peaks are rather broad, indicating the small crystallite size of the electrodeposited Al. The grain size of Al was determined using Scherrer s equation to be 34 nm. For more information on the electrodeposition of nanocrystalline aluminum in the employed ionic liquid we refer to Refs. [3, 4]. 

The unique moment of discovery came in April 1982 when Dan Shechtman was doing some electron diffraction experiments on alloys, produced by very rapid cooling of molten metals. In the experiments with molten aluminum with added magnesium, cooled rapidly, he observed an electron diffraction pattern with tenfold symmetry (see, the pattern in the Introduction). It was as great a surprise as it could have been imagined for any well-trained crystallographer. Shechtman s surprise was recorded with three question marks in his lab notebook, 10-fold [140],... 

Quasicrystals are solid materials exhibiting diffraction patterns with apparently sharp spots containing symmetry axes such as fivefold or eightfold axes, which are incompatible with the three-dimensional periodicity associated with crystal lattices. Many such materials are aluminum alloys, which exhibit diffraction patterns with fivefold symmetry axes such materials are called icosahedral quasicrystals. " Such quasicrystals " may be defined to have delta functions in their Fourier transforms, but their local point symmetries are incompatible with the periodic order of traditional crystallography. Structures with fivefold symmetry exhibit quasiperiodicity in two dimensions and periodicity in the third. Quasicrystals are thus seen to exhibit a lower order than in true crystals but a higher order than truly amorphous materials. 

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