Rare-carth oxides with fluorite-related structures: their systematic investigation using HREM images, image, image simulations and electron diffraction pattern simulations

摘要

A complete set of non-equivalent kinematicelectron patterns corresponding to the main zone axis orientations,<1 0 0 >F, <1 0 0 >F ,<1 1 1>Fand <1 1 2> F have beencalculated for most members of the homologous series of binaryanion-deficient, fluorite-related higher oxides of the rare earthelements, whose structures are currently resolved or postulated onthe basis of the "fluorite-type module theory". From an analysis ofthis set, specific electron diffraction patterns which allow anunequivocal identification of each phase can be sorted out. Asystematic approach, based on the use of these calculated patterns,to make a reliable phase identification for any sample that containsa mixture of these phases is presented and applied to interpretdifferent experimental electron diffraction patterns. The detailedinterpretation of a number of experimental HREM imagesrecorded on a sample of praseodymium oxide using a match withcalcuated images is also illustrated. These results and proceduresprovide supplementary confirmation of the fluorite-type moduletheory to explain the structural features of the higher rare earthoxide phases and provide the bank ground necessary to characterizethese materials reliably.