INFLUENCE OF 85 MEV OXYGEN-ION IRRADIATION ON MAGNETIZATION BEHAVIOR OF MICRON-SIZED AND NANO-SIZED POWDERS OF STRONTIUM FERRITE (SRFE12O19)

The consequences of 85 MeV O-16 ion irradiations on the magnetization behavior of micron-sized and nano-sized powders of hexagonal ferrite ( SrFe12O19) are examined. The powders were characterized by vibrating s ample magnetometery (VSM), Mossbauer spectroscopy and scanning electro n microscopy (SEM). Significant changes in hysteresis loop features ar e observed after irradiation in the case of micron-sized powders, wher eas no change is seen in the case of nano-sized powders. The issue of stability of defect states in small systems based on the consideration of elastic energy is discussed. (C) 1998 Elsevier Science B.V. All ri ghts reserved.