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On the origin of core losses in a manganese zinc ferrite with appreciable silica content
G. C. Jain, B. K. Das, and Santosh Kumari
Citation: Journal of Applied Physics 49, 2894 (1978); doi: 10.1063/1.325173
View online: http://dx.doi.org/10.1063/1.325173
View Table of Contents: http://scitation.aip.org/content/aip/journal/jap/49/5?ver=pdfcov
Published by theAIP Publishing
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128.138.73.68 On: Mon, 22 Dec 2014 05:20:35
http://scitation.aip.org/search?value1=G.+C.+Jain&option1=authorhttp://scitation.aip.org/search?value1=B.+K.+Das&option1=authorhttp://scitation.aip.org/search?value1=Santosh+Kumari&option1=authorhttp://scitation.aip.org/content/aip/journal/jap?ver=pdfcovhttp://dx.doi.org/10.1063/1.325173http://scitation.aip.org/content/aip/journal/jap/49/5?ver=pdfcovhttp://scitation.aip.org/content/aip?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/apl/94/7/10.1063/1.3083555?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/81/12/10.1063/1.365393?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/53/2/10.1063/1.330525?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/35/5/10.1063/1.1713704?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/29/3/10.1063/1.1723124?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/29/3/10.1063/1.1723124?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/35/5/10.1063/1.1713704?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/53/2/10.1063/1.330525?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/81/12/10.1063/1.365393?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/apl/94/7/10.1063/1.3083555?ver=pdfcovhttp://scitation.aip.org/content/aip?ver=pdfcovhttp://scitation.aip.org/content/aip/journal/jap/49/5?ver=pdfcovhttp://dx.doi.org/10.1063/1.325173http://scitation.aip.org/content/aip/journal/jap?ver=pdfcovhttp://scitation.aip.org/search?value1=Santosh+Kumari&option1=authorhttp://scitation.aip.org/search?value1=B.+K.+Das&option1=authorhttp://scitation.aip.org/search?value1=G.+C.+Jain&option1=authorhttp://oasc12039.247realmedia.com/RealMedia/ads/click_lx.ads/www.aip.org/pt/adcenter/pdfcover_test/L-37/884760910/x01/AIP-PT/Asylum_JAPArticleDL_121014/AIP-JAD-Cypher1.jpg/47344656396c504a5a37344142416b75?xhttp://scitation.aip.org/content/aip/journal/jap?ver=pdfcov7/26/2019 penelitian aip
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nthe origin of core losses
in
a manganese zinc ferrite
with appreciable silica content
G C
Jain, B K. Das, and Santosh Kumari
Division o Materials. National Physical Laboratory. New Delhi 110012. Ind ia
(Received 25 March 1977; accepted for publication
10
June 1977)
The effect
of
silica on the magnetic properties and microstructure of a manganese zinc ferrite has been
studied. It is found that as silica content increases. the magnetic properties
at
first improve. then
deteriorate around 0.04% silica due to discontinuous grain growth. At still higher silica contents.
magnetic properties deteriorate further due to an increase in the total effective magnetic anisotropy.
PACS numbers: 75.50.0g, 81.40.Rs, 75.60.Ej
I. INTRODUCTION
Silica is
the main impurity in most of the raw
mate
rials used in the preparation of ferrites, especially
ferric oxide, and it is known to affect the various
magnetic properties of Mn- Zn
fer rites
significantly.
I t has therefore become necessary to understand the
effect of the
silica
content in Mn- Zn
ferrites
in order
to
prepare
ferrites with
reasonable properties
using
comparatively
impure
raw
materials.
Manyauthors
t -
3
have studied the effect of small additions of Si 0
2
on the
microstructure and the low-field properties of ferrites.
The present work
deals
with a study of power
losses
at high flux densities and microstructure with different
Si0
2
contents. This owes
its
importance
in developing
a Mn- Zn ferrite with low
core
losses for high-frequency
power application using raw
materials
containing
ap
preciable silica.
II. EXPERIMENTAL METHODS
Mn-Zn ferrite of basic formula
M l l o 5 6 4 Z l l o 3 7 4 F ~ o 6 0 4
was prepared to which various amounts of
silica
ranging
from O.
01
to
0.64%
(all
silica
percentages
are
weight
percents) were added using usual ceramic techniques.
Initial raw
materials
contained
less
than
O. 01
%
silica.
The
toroids pressed
out of these. were fired in a pure
nitrogen atmosphere at 1275 C for
45
min and cooled
in
pure
nitrogen.
3000
t
~ 2 5 0 0
::::i
iii
~ 2 0 0 0
::IE
a:
w
Q,
1500
...J
c
i=
1000
Mn
O
IM
Zn
O174
Fe;&O.0
4
12nSC/45mln. N
z
Core Ios.e. /
/
- - - - ~
'
.. '
....... , '
--
-----
SiO
z
CONTENT IN
W T . ~ -
'
/
I
/
/
FIG. 1. Initial
permeability
and core losses
at
2000 G
and
15.75
kHz
vs
silica
content.
Power-loss measurements
were
taken on
toroids
(0. d. =::
1.
36 cm,
i.
d. =:: 0.84 cm, and thickness =:: 0.21
cm) at a peak flux density of 2000 G and up to a fre
quency of 15.75 kHz. An
incremental
inductance
bridge
type 1633-A with an inductance-measuring assembly
type 1630-AV (General Radio Company,
USA
was used
for
this purpose.
Hysteresis curves
were
also
pictured
under the
same
conditions on a loop
tracer.
Microstructures
of
these
samples were
observed
after etching the
metallographically
polished
specimen
in a 3 : 1 solution of hydrochloric acid in ethyl alcohol.
In order to locate the
silica
distribution a scanning
electron microscope in
its
x-ray mode was used.
III.
RESULTS
A. Magnetic properties
Figure 1 gives the
initial permeability
III and power
loss density as a function of Si0
2
addition.
IJ.j
at first
increases with silica content up to 0.02%, falls off and
remains constant up to
o
16%
Si0
2
, and then
drops
further at the two highest
silica
contents. At 15.75
kHz,
power-loss
density shows a peak
at
the
silica
content of 0.04% and then a rise at the two highest
silica contents. Figure 2
gives
power-loss denSity/kHz
for
different
frequencies.
Intermediate levels of silica
N
J:
>
e'
( )'"
'
::E
K
500
200
400
0
01 '02
04
08
'16
32
64
i 02
content in wt
FIG.
8.
Ms.
K. and
7/26/2019 penelitian aip
5/5
total
effective anisotropy causes the
slanting
of the
B-H
loop and therefore the
increase in
the
losses.
In order to explain the
behaviour
of initial permeabil
ity,
the product MsD/K1 2,
where
D, is the
average
intragranular pore-to-pore distance
or the grain
diam
eter,
whichever
is
smaller, is
plotted
against the silica
content Fig. 8 and
it
can
be seen that the behavior
is
similar to that of IJ.j. Globus
12
and
Das
and
Chaudhari
t3
have shown that the domain
wall
contribution
to
I l i
is
given by
I l i
-
1 M Dh,
where
y is the domain
wall
energy
[=
(AK)t ] and A
is
the exchange constant - M;
I t means that in
these
ferrites the initial
permeability
is dominated by the contribution due to the domain wall
bulging.
CKNOWLEDGMENTS
The
authors
wish to express their appreciation to
Dr.
A. Hepworth of Indian Institute of Technology,
Delhi,
for
the scanning
electron
microscope analysis
and
Dr.
S.
P. Bhattacharjee for
h l p ~ u l
discussions.
2897 J. Appl. Phys., Vol. 49,
No.5
May 1978
They also thank Dr. A. R. Verma, Director, National
Physical Laboratory, for granting
the permission to
publish this
work.
IT.
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Trans. Jpn.
Inst.
Met. 2, 171
1961).
2T.
Akashi,
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F.
Pearson, J. E.
Knowles, and P.
Rankin,
Ferrites: Proc. Int. Conf. ,
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1970, p. 194 unpublished).
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Giles and
F.F.
Westendorp, J . Phys. to be
published).
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Ref. 3, p.
137.
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1975).
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et
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2897
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