ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The MoO3 structure is analysed by means of multi-slice calculations for crystals up to 80 Å thick. It is shown that for such thin crystals convergent-beam patterns can be simply analysed. This allows crystal thickness to be readily determined and opens up the way to more precise structure factor measurements. Many-beam calculations are also used to analyse unit-cell and symmetry data obtained by convergent-beam diffraction/microscopy observations of '101' domains in molybdenum trioxide, showing that [MoO6] octahedra in domains are more nearly regular than in MoO3. This is supported by analysis of thermal diffuse scattering. The '101' domain structure has space group Cmcm and unit-cell parameters identical to those of the molybdenum oxide-hydroxide Mo4O10(OH)2. A qualitative comparison of calculated and observed intensities for the space-group-forbidden 100 reflexions of MoO3 indicates the presence of epitaxically deposited surface layers. This observation, together with the evidence of a hydroxylated domain structure, suggests that thin crystals are formed with epitaxic hydroxyl layers which diffuse into the bulk structure when the crystals are heated.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739478000558
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