Effect of doping a Mn-Zn ferrite with GeO<inf>2</inf>and SnO<inf>2</inf>

Abstract

The effects of various additions of GeO 2 or SnO 2 , in a Mn-Zn ferrite on the microstructure and magnetic properties have been studied. The behavior of GeO 2 additive has been found to be similar to that of SiO 2 . Up to a GeO 2 content of 0.64 mol%, the magnetic properties improve through the increase in the density. At a higher GeO 2 content of 1.28 mol%, the properties deteriorate due to the occurrence of discontinuous grain growth. Further addition of GeO 2 gives better grain structure but poor properties. The presented results suggest that Ge4+dissolves in the ferrite to a very limited extent and GeO 2 exists as a second phase. SnO 2 , on the other hand, has been found to be soluble in the ferrite and does not alter the microstructure even up to a content of 5.70 mol%. The essential property of this additive is found to be in its ability to modify the variation of μ i with temperature without deteriorating the μ i and core losses. The temperature variation of the bulk resistivity has also been studied.