Phase distribution and magnetic properties of hard/soft ferrite nanocomposites prepared through mechanical alloying and physical mixing method
Nanocomposite magnet consisting of hard and soft magnetic phases has attracted many attentions from the researcher in recent years. The exchange coupling between hard and soft phase can combine the high coercivity of the hard phase and the high magnetization of soft phase to produce a magnet with...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2019
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/90029/1/FS%202019%2082%20ir.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Nanocomposite magnet consisting of hard and soft magnetic phases has attracted
many attentions from the researcher in recent years. The exchange coupling between
hard and soft phase can combine the high coercivity of the hard phase and the high
magnetization of soft phase to produce a magnet with high energy product. The
mechanical alloying and physical mixing method are chosen to produce the
nanocomposite. The hard phase, SrFe12O19 and soft phase, Ni0.5Zn0.5Fe2O4 were
mixed to become nanocomposite SrFe12O19/Ni0.5Zn0.5Fe2O4. The effect of phase
distribution in the nanocomposite is studied by varying the amount of soft ferrite.
While the amount of hard ferrite is kept constant. The novelty of this research lies in
the different phase distribution between hard and soft phases in the nanocomposite,
which gives more understanding of the effect of phase distribution on the exchange
coupling.
The characterizations of the samples are carried out using Thermogravimetric
Analysis (TGA), X-ray Diffraction (XRD), Vibrating Sample Magnetometer
(VSM), Electron Paramagnetic Resonance (EPR) and microstructure analysis using
Transmission Electron Microscope (TEM) and Field Emission Scanning Electron
Microscope (FESEM). The XRD results on the nanocomposites shown that both hard
phase, SrFe12O19 and soft phase, Ni0.5Zn0.5Fe2O4 are present in the samples producing
the SrFe12O19/Ni0.5Zn0.5Fe2O4 nanocomposite. From the mechanical alloying method,
the nanocomposites with 10-20 wt.% of soft phase content shown the remanence
ratio, Mr/Ms ≥ 0.5. The best result is from nanocomposite with 20 wt.% soft phase
with the values of Hc and Ms are 3313.7 G and 36.3 emu/g, respectively. While, for
physical mixing, the nanocomposites with 10-30 wt.% of soft phase content shows
Mr/Ms ≥ 0.5. With the best result is from nanocomposite ferrite with 30 wt.% soft
phase with the values of Hc and Ms are 2926.3 G and 45.5 emu/g, respectively. We
also manage to get the average particle size for the nanocomposites < 50 nm for both methods. From the results, it is found that the exchange coupling in the
nanocomposites is affected by the phase distribution between the hard and soft
phases as the amount of soft phase increase in the nanocomposite, the coercivity and
magnetization decrease. For example, the magnetization for the nanocomposites
prepared by physical mixing method decrease from 45.5 to 5.0 emu/g for
nanocomposite with 30-100 wt.% of soft phase content. The optimum amount of soft
phase needed in the nanocomposite is found to be 20-30 wt.% to maximize the effect
of the exchange coupling between the hard and soft ferrites. |
|---|