Abstrakt
Small particles of magnetite, i.e. 7.5, 13.4 and 14.1 nm in diameter, were obtained by the method of
co-precipitation. The crystal structure and size distributions were determined by means of transmission electron
microscopy and X-ray diffraction. The magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy
within the temperature range from 3 K to room temperature (RT). The Mössbauer study of magnetic
nanoparticles reveals relaxation behaviour related to the existence of the superparamagnetic phase. The blocking
temperature depends on the sizes of the nanoparticles and the ammonia concentration