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abstract
There were many kinds of methods to prepare the Mn-Mg
ferrites.In this paper,the auther used chemical co-
precipitation suscessfully to make up the fine precipitates
,including Mn(OH)2,Mg(OH)2 and Fe(OH)2,with the condition
of PH=11and T=60℃.Then,the pure manganese-magnesium
ferrites about 0.1um had been prepared after the
predipitates were calcined at 800℃ for 1hr.
It iwas known that the densification of the sintered
samples affected the magnetic properties very much,so the
samples pressed at the pressure of 1000kg/cm2 were tried
to sinter during the range of 1150-1350℃and 1-16hr in the
experment,and then we could discuss its change for magnetic
properties.Besides,the Bi2O3,ZnO were added to improve
ferrites' magnetic properties.
After the experiment results,it was verified that the
manganese-magnesium ferrites sintered at 1300℃,12hr had
better magnetic properties: Bm(maximum induction)=2200
Guess ,Hc(coercive force)=1.1Oe,and R(squareness ratio
=90%.however,the lowest loss(2.2×10-4 at 4MHz)was got
by sintering at 1250℃for 8hr.Besides,it was found that
the ferrites added 0.2wt% Bi2O3 had high initial
permeability,low coercive force and good squareness ratio
at lower temperature.In addition,the ferrites added ZnO
resulted in increasing the initial permeability very much
and decreasing the coercive force,but increasing the loss
factor fast at higher frequency(10MHz).
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