Strained lattice

In addition, diffraction line breadth contains information on lattice strain, lattice defects, and thermal vibrations of the crystal structure. The chief problem to determine crystallite size from line breadth is the determination of /3(20) from the diffraction profile, because broadening can also be caused by the instrument. To correct for the instrumental broadening on the pattern of the sample, it is convenient to run a standard peak from a sample in which the crystallite size is large enough to eliminate all crystallite size broadening. By use of a convolu-... 

The r-time curves for the decomposition of anhydrous cobalt oxalate (570 to 590 K) were [59] sigmoid, following an initial deceleratory process to a about 0.02. The kinetic behaviour was, however, influenced by the temperature of dehydration. For salt pretreated at 420 K, the exponential acceleratory process extended to flr= 0.5 and was followed by an approximately constant reaction rate to a = 0.92, the slope of which was almost independent of temperature. In contrast, the decomposition of salt previously dehydrated at 470 K was best described by the Prout-Tompkins equation (0.24 < a< 0.97) with 7 = 165 kJ mol . This difference in behaviour was attributed to differences in reactant texture. Decomposition of the highly porous material obtained from low temperature dehydration was believed to proceed outwards from internal pores, and inwards from external surfaces in a region of highly strained lattice. This geometry results in zero-order kinetic behaviour. Dehydration at 470 K, however, yielded non-porous material in which the strain had been relieved and the decomposition behaviour was broadly comparable with that of the nickel salt. Kadlec and Danes [55] also obtained sigmoid ar-time curves which fitted the Avrami-Erofeev equation with n = 2.4 and = 184 kJ mol" . The kinetic behaviour of cobalt oxalate [60] may be influenced by the disposition of the sample in the reaction vessel. 

Strain Relaxation in Quantum Wires and Etched Quantum Dots In the fabrication of etched quantum wires and quantum dots, the strain caused by lattice mismatch in MBE-grown layers is partially reduced by the etching process. At the lateral surfaces of these structures, a possibility exists for the strained lattice to relax. Therefore, the amount of the total relaxation depends on the ratio of the relaxed wire edges to the total volume of the wire. Thus, for a reduction of the wire dimensions, like the reduction of the wire width or the wire length, a reduction of the total amount of the strain is possible. The wire edges can relax, whereas the wire center remains strained. 

When the particle positions in the strained lattice around a dislocation are known from confocal microscopy, one can test the contrast of the lines quantitatively, as illustrated by the example of Fig. 7. The amplitude of a point P in the image plane below a crystal is given by ... 

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