Transmission electron microscopy stacking faults

The majority of dislocation loops and stacking faults observed by transmission electron microscopy of Si are judged to be of extrinsic or interstitial character. Although there are four proposed mechanisms by which extrinsic-type dislocations may be formed without any self-interstitials being present (12), most workers believe that self-interstitial precipitation is the dominant mechanism in extrinsic-type dislocations. 

B-TEM sanple corresponding to the above specimen. From the B-ThM saitples, it was possible to conduct detailed TEM analysis which gave the follcwing information on the above defects. Dislocation loops at depth level I were dominantly a/3 <111> type and extrinsic (extra layers) in nature. The tips of the hair-pin dislocations were of the same character as at I, however, the arms of the hair-pins lay along all six <110> directions. The defects in layer III were found to be stacking fault bundles and microtwins by atomic resolution transmission electron microscopy (17). 

Carl] Carpenter, S.D., Carpenter, D., Stacking Faults and Superlattice Observations During Transmission Electron Microscopy of a (Fe,Cr)7C3 Ca bide , Mater. Lett., 57(28), 4460-4465 (2003) (Crys. Stracture, Morphology, Experimental, 9)... 

Transmission electron microscopy, electron diffraction, and Raman spectroscopy indicated that the (001) growth sector has less defects, whereas the (111) sector shows many stacking faults and twins. Epitaxy on the ((X)l) surface of diamond was the first choice in searching for electronic quality films. 

For the actual partials in face-centered cubic metals being discussed, w = Ga l24ny. The spacing for aluminum, which has a high stacking fault energy, computes to about one atom diameter. Extended dislocations are thus not expected in aluminum and they are not observed. The width for austenitic stainless steel computes to about 1 x 10" cm. Extended dislocations are commonly observed in austenitic stainless steel by transmission electron microscopy. 

The isotherm of H-Beta is reported in figure 4 and exhibits an hyterisis loop indicating that mesopores are present, the closer point of the hyterisis loop is found to be close to P/Po=0.42. Catastrophic desorption of mesopores is seen as generally found for dealuminated HY zeolites (ref. 8), one can discuss about the origin of this phenomenon. It is certainly due to mesopores, evidenced in transmission electron microscopy, which are not directly connected to the exterior of the crystals. The formation of these mesopores is probably related to the presence of faults in the stacking sequence of polytypes as mentioned in ref. 9. 

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