Due
to the issues associated with rare-earth elements, there arises
a strong need for magnets with properties between those of ferrites
and rare-earth magnets that could substitute the latter in selected
applications. Here, we produce a high remanent magnetization composite
bonded magnet by mixing FeCo nanowire powders with hexaferrite particles.
In the first step, metallic nanowires with diameters between 30 and
100 nm and length of at least 2 μm are fabricated by electrodeposition.
The oriented as-synthesized nanowires show remanence ratios above
0.76 and coercivities above 199 kA/m and resist core oxidation up
to 300 °C due to the existence of a >8 nm thin oxide passivating
shell. In the second step, a composite powder is fabricated by mixing
the nanowires with hexaferrite particles. After the optimal nanowire
diameter and composite composition are selected, a bonded magnet is
produced. The resulting magnet presents a 20% increase in remanence
and an enhancement of the energy product of 48% with respect to a
pure hexaferrite (strontium ferrite) magnet. These results put nanowire–ferrite
composites at the forefront as candidate materials for alternative
magnets for substitution of rare earths in applications that operate
with moderate magnet performance.
We here present a simple model of a vibrating sample magnetometer (VSM). The system allows recording magnetization curves at room temperature with a resolution of the order of 0.01 emu and is appropriated for macroscopic samples. The setup can be mounted with different configurations depending on the requirements of the sample to be measured (mass, saturation magnetization, saturation field, etc.). We also include here examples of curves obtained with our setup and comparison curves measured with a standard commercial VSM that confirms the reliability of our device.
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