New Developments in Ferromagnetic Materials

Abstract

QUITE apart from any other, this brochure is of interest as illustrating some of the work done by Dutch men of science during the period of the German occupation. Starting off with general accounts of what the author terms the statics and dynamics of ferromagnetism, the main interest lies in the work done on the development of new magnetic materials based on the cubic MO.Fe₂O₃ compounds. The interesting fact emerges that the oxides containing zinc have higher permeabilities than the rest, presumably because the Curie point is lowered, the maximum permeability being found to occur just below this temperature. The samples are prepared by a sintering technique which is described, and in the case of mixed NiO, ZnO compounds, a maximum initial permeability of 4,000 has been obtained. Among the appendixes is one dealing with the decarburization of steel. The author claims that the rate of diffusion of carbon in α-iron is very much higher than that in the γ-modification, a view which is contrary to current opinion, and which requires further confirmation before it can be accepted.

New Developments in Ferromagnetic Materials

With Introductory Chapters on the Statics and the Dynamics of Ferromagnetism. By J. L. Snoek. (Monographs on the Progress of Research in Holland during the War.) Pp. viii + 136. (New York and Amsterdam : Elsevier Publishing Co., Inc., 1947.) 6.75 fl.