| Summary: | 碩士 === 國立屏東大學 === 應用物理系碩士班 === 104 === Curie temperature is the temperature at which certain materials lose their permanent magnetic properties, to be replace by induced magnetism. At normal condition the nanoparticle magnetization will flip several times during the measurement, then the measured magnetization will average to zero. At the blocking temperature, the magnetization will not flip during the measurement, so the measured magnetization will be what the instantaneous magnetization was at the beginning of the measurement.
To the best of our knowledge no report on size dependent optical behavior in the vicinity of the blocking temperature has been found in literature. In this work, we synthesized Ni0.2Zn0.8Fe2O4 nanoparticles by the combustion method. Use X-Ray Diffraction to analyze the Ni0.2Zn0.8Fe2O4 ranging from 15.5 to 50.0 nm. Then used the Raman spectroscopy and magnetic measurements to study the size effects on the magnetic phase transition in the vicinity of the compensation point.
The Ni0.2Zn0.8Fe2O4 NPs used a special way in MCD(Magnetic Circular Dichroism) to realize the difference between light polarized optics and right polarized optics. To the result, the diameter ³ 41.9 nm difference in absorption is very small. It can know that is paramagnetic at room temperature form SQUID data. That’s the reason of MCD’s result.
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