CRYSTAL DEFECTS IN FLUX GROWN LITHIUM FERRITE, LIFE5O8 SINGLE-CRYSTALS

With the increase of frequencies in microwave communications lithium ferrite single crystals attract growing interest. The characteristic crystal defects of a flux-grown LiFe5O8 single crystal were investigated by means of light microscopy, scanning electron microscopy and X-ray topography with respect to the technology. At the beginning of the growth process crystal grains with slightly different orientations and with boundaries containing dislocation groups were formed. Thermal stresses caused cracks. The curved cracks were accompanied by strain fields of helices partly decorated by precipitates visible on the topographs and also by light microscope. Far from the nucleation site of the crystal large perfect regions containing only straight small-angle boundaries could be found. Precipitates, presumably of LiFeO2, were present in all parts of the crystal. Dislocation arrangements characteristic of stacking faults also appeared on the crystal. © 1979 with the authors.