Sol-gel Synthesis, Structural and Magnetic
Properties of Nano Scale Strontium Hexaferrites
K. Alamelumangai1*., Dr. M. Priya2 ., Dr. M. Rathnakumari3 ., Dr. P. Sureshkumar3
1
Asst. Prof., Department of Physics,VelTech HighTech Engineering College, Avadi, Chennai.
Associate Prof., Department of Physics, Saveetha Engineering College, Thandalam, Chennai.
3
Professor., Department of Physics, Velammal Engineering College, Surapet, Chennai.
e-mail: gmangai4782@gmail.com, Tel.: 9443836550
2
Abstract
In this paper, a batch of M- type strontium hexaferrite
samples with nominal stoichiometric rartioof SrFe12O19,
have been synthesized via sol- gel method. In the
synthesis of samples, first a precursor gel was prepared,
and then dry- gel was calcined from 600°C to 1000°C for
96 hours to obtain the nano- SrFe12O19. The XRD results
revealed that for SrFe12O19 samples with these
calcination temperatures, all of them have single- phase
hexaferrite structure and also this data suggests that the
impurity iron oxide phase is preferentially formed when
strontium content is low and at low calcination
temperature. The magnetic properties, such as saturation
magnetization (Ms), magnetic remanence (Mr), magnetic
coercivity (Hc), squareness ratio (Mr/Ms), crystalline
anisotropy field (Ha), energy product [(BH)max] and the
susceptibility χ as the derivative of M with respect to H
of the upper branch of the hysteresis loop were discussed
by measurements of M-H curves with vibrating sample
magnetometer (VSM). The magnetic measurements
revealed that the coercively (Hc) values of all the
samples decrease with increasing the calcination
temperature.
Index Terms—Hexa ferrite; Nanoparticle; Sol–gel
technique; SEM; VSM;
Introduction
Magnetic nanoparticles are important physical
systems, relevant for many applications, and in
many cases the starting point of fundamental
developments in Nano magnetism. Magnetic
nanomaterials are used in information recording
and storage systems, in new permanent magnets, in
magnetic cooling systems, as magnetic sensors, etc.
Strontium ferrite is widely used as a permanent
magnetic material due to its high uniaxial
-20000
0
anisotropy and co-ercivity. It is also used in sound
and data storage technology, micro motors for
cassette and video tape recorders, television
technology, generators, speaker magnets, magnet
clamps and retainers for mechanical engineering,
and magnetic snap-lock strips for furniture and
refrigerators.
Results and Discussions
In the paper, sol-gel method was applied in the
preparation of SrFe12O19 with ferric nitrate,
strontium nitrate and ethylene glycol as starting
reagents. M-type strontium ferrite nano powders
are obtained subsequently from calcination of these
precursors at 1000˚ C. The as-synthesized particles
were characterized by FTIR, XRD and SEM and
was used to study the effect of the material
component, the types of surface treatment agent,
the
structure
and
morphology on the
electromagnetic properties of samples. The particle
size for the samples were influenced by the metal
salt concentration in solution and it was found to be
around 10nm.
The magnetic properties such as saturation
magnetization (Ms), remanence (Mr), coercivity
(Hc), squareness ratio (Mr/Ms), crystalline
anisotropy
field
(Ha),
magnetocrystalline
anisotropy constant (K), demagnetizing field (Hd),
energy product [(BH)max] and the susceptibility χ
(χ= dM/dH) as the derivative of M with respect to
H of the upper branch of the hysteresis loop were
deduced from measurements of M- H curves which
have been done by vibrating sample magnetometer
(VSM) at room temperature at a maximum applied
field of 20 kOe.
20000
40
References
30
20
10
1000°C
0
-10
-20
Moment/Mass (emu/g)
-30
-40
40
20
800°C
0
-20
-40
46
23
600°C
0
-23
-46
-20000
0
Magnetic field (G)
20000
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[2]. M. J. Iqbal, M. N. Ashiq and P. H. Gomez:
Alloys and Compounds Vol. 478 (2009), p. 736