磁性細菌AMB-1から分離した磁性微粒子の磁気的性質 Magnetic Characterization of Bacterial Magnetic Particles
The experimental results on Mössbauer measurement, chemical analysis (a ratio of Fe<SUP>2+</SUP> to total Fe content), analyses of the rotational hysteresis loss (Wr) and the measurement of magnetic viscosity coefficient (Sv) for bacterial magnetic particles (BMP, particle diameter D=25-65 nm) were compared with those of Fe<SUB>3</SUB>O<SUB>4</SUB> particles (D=18-45 nm) prepared by the chemical coprecipitated method. The value of saturation magnetization (Js) calculated from Mössbauer spectrum and the results of chemical analysis for BMP was 1.06×10<SUP>-4</SUP> Wb m/kg. The curves of Wr/Ms versus H for BMP showed more sharp peaks than those of Fe<SUB>3</SUB>O<SUB>4</SUB> particles. The rotational hysteresis integral (Rh) of BMP and Fe<SUB>3</SUB>O<SUB>4</SUB> particles were 1.12 and 0.62, respectively. It was considered that they have different magnetization reversal mechanism. Sv value of BMP was 127 A/m, which was 50% smaller than that of Fe<SUB>3</SUB>O<SUB>4</SUB> particles. The diameter (Dact) of activation volume (minimum unit volume of magnetization reversal) calculated from Sv and the critical diameter (Dc) obtained by considering the superparamagnetic behavior of BMP, were 39 and 22 nm, respectively. On the other hand, Fe<SUB>3</SUB>O<SUB>4</SUB>particles had smaller Dact (31nm) and Dc (18nm). It maybe concluded that the magnetic stability of BMP is better than that of Fe<SUB>3</SUB>O<SUB>4</SUB> particles.
粉体および粉末冶金 43(8), 1036-1041, 1996-08-15
Japan Society of Powder and Powder Metallurgy