Viktor Kraševec

A new monoclinic phase in the Fe2O3TiO2 system. I. Structure determination and Mössbauer spectroscopy

Abstract Single crystals with compositions within the Fe 2 O 3 TiO 2 system were grown from a flux containing various amounts of the basic oxides. Apart from the known pseudobrookite (Fe 2 TiO 5 ) and rutile (TiO 2 ) structures, a new monoclinic polytype of Fe 2 TiO 5 was found, which was isostructural with V 3 O 5 . The structure was determined by X-ray analysis and Mossbauer spectroscopy contributed data on hyperfine parameters and the magnetic ordering temperature.

A new monoclinic phase in the Fe2O3TiO2 system. II. The defect structure

Abstract Defects in monoclinic Fe 2 TiO 5 were studied by electron microscopy and diffraction. The monoclinic structure found, which is isostructural with V 3 O 5 , can be derived in a simple way from a hexagonal close-packed structure and can be considered as a member of the family of crystallographic shear structures, derived from rutile. Two different slips corresponding to two hexagonal basal ones, were found to cause stacking faults, antiphase boundaries, and two different crystallographic shear planes.

Influence of Chemical Composition on the Barrier Height in ZnO Varistors

ZnO-based varistors exhibit highly nonlinear electrical characteristics, which are due to the electrical properties of the grain boundary regions.