ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Lattice images of high-temperature-phase vanadium sesquioxide (V2O3) were calculated within the Bloch-wave approach. At an accelerating voltage of 1000 kV the structure image can be produced while at 100 kV it cannot be obtained because of the small number of reflections available in the image formation, which demonstrates clearly an advantage of high voltages which are produced by improvement in the transfer condition of the objective lens. On the other hand, if an ideal phase-contrast lens is assumed in order to obtain the structure image at 100 kV, lattice-image calculations can be carried out with modified unit-cell size. The results show that the maximum allowable thickness to obtain the structure image varies more rapidly than in a linear manner with the required resolution. The maximum allowable thickness increases either with higher voltages (from about 20 Å at 100 kV to about 35 Å at 1000 kV) or with larger unit cells (e.g. a dilatation of 25% in unit-cell size increases the maximum thickness from about 20 to about 35 Å). However, the evolution of the image details as a function of crystal thickness is different for these two factors, due to the different dynamical interactions of electron waves.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739480002094
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