DELINEATION OF DEFECTS IN FLUX GROWN STRONTIUM HEXAFERRITE CRYSTALS. P.N. Kotru, Urvashi Raina and Sushma Bhat, Dept. Of Physics, University of Jammu, Jammu, India and F. Licci, Instituto MASOPEC-CNR, via chiavari 18/A, 43100 Parma Italy

Results of etching (0001) planes of flux grown strontium hexaferrite crystals in 85% H₃PO₄ at 120deg.C and 37% HCl at 100deg.C are presented. Fractography reveals one to one correspondence of cleavage patterns on the two matched (0001) cleaved planes. Experiments on successive etching of grain boundaries established H₃PO₄ and HCl under the above given conditions as the dislocation etchants. Several types of etch pit structures are illustrated. It is explained that they are indicative of normal, inclined, stepped and bending dislocations in these crystals. Pit structures due to impurity inclusions are discussed. The explanations are supported by the results of mismatchings of etch patterns on matched cleavages.