Manganese zinc ferrite with high initial permeability - contains germanium di:oxide to increase density after sintering

摘要

with high quality and low porosity, where the compsn. of the starting materials (a) in mole % is:- 49 to 54% Fe2O3, 10-40 MnO, rest ZnO; and with (wt.%) 0.05-1% GeO2, and 0.03-1% CaO. Up to 5% Fe2O3 may be replaced by TiO2 and/or SnO2; and materials (a), with the usual commercial purity, pref. contain a total of 0.005-0.05% SiO2 by wt. In the pref. mfg. process, the materials (a) without the CeO are mixed; opt. presintered; milled; the CaO added as CaCO3; mixed; pressed into mouldings; heated In N2 to a sintering temp. to 1150-1250 degrees C; sintered in N2 contg. O2; and cooled in N2 contg. a decreasing amt. of O2. The GeO2 addn. raises the density so cores made of two half shells can easily be joined together by an adhesive; and low losses are obtd. over a wide range of frequencies and temp.