Hyperfine fields and magnetic properties of barium monoferrite

First we studied the kinetics of the formation of Ba monoferrite by means of Moessbauer spectroscopy. The most important result is the considereable portion of hexaferrite existing after treatment of the starting materials between 800 and 900deg C, caused by a higher rate of diffusion of the Ba2+ ions in comparison to the Fe3+ ions. Second we report susceptibility measurements recorded in a temperature range of 4.3 K to 280 K and Moessbauer spectra at room temperature and at 4.2 K without and in the presence of an applied magnetic field of 6 T. The experimental data demonstrate that the magnetic behaviour of Ba monoferrite deviates to some extent from a simple antiferromagnetic. (orig.)