Magnetic Behaviors and Spectroscopic Studies of A0.5Zn0.5Fe2O4(A=Mn,Ni) Nanoparticles

• Main Authors: WU, TAN-XUAN, 吳坦軒
• Other Authors: LIN, CHUNG-RONG
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/4uprfm

碩士 === 國立屏東大學 === 應用物理系碩士班 === 106 === 　　Ni0.5Zn0.5Fe2O4 and Mn0.5Zn0.5Fe2O4 nanoparticles can be synthesized by Pyrolysis, and the temperature and time can be used to change the average crystal size. Samples will be measured by using X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetic circular dichroism (MCD) and Raman spectroscopy (Raman) 　　When the average particle size (d) increases, the saturation magnetization (Ms) of the two series of samples will tend to grow. The coercivity (Hc) of Ni0.5Zn0.5Fe2O4 first grows with the average particle size (d), then shows a maximum at an average particle size of 16.42 nm, and then decreases with the growth of the average particle size. This phenomenon indicates that there has been a shift in the magnetic domain. The coercive field (Hc) of Mn0.5Zn0.5Fe2O4 is very weak, and there is no significant increase even if the particle size grows significantly. In the MCD research, we use the Gaussian function to do the spectrum analysis. The results show that the incident light at different wavelengths can correspond to different electronic excitation patterns, such as IVCT, ISCT and crystal field (CF). The MCD signal of Ni0.5Zn0.5Fe2O4 is slightly red-shifted, and the cation distribution is disordered at an average particle size of 16.42 nm. Mn0.5Zn0.5Fe2O4 is inconsistent in excitation energy due to disordered and irregular cation distribution. In the Raman spectroscopy study, we use the Lorentz function to perform spectral analysis. The results show that the crystal structure of the sample is a cubic structure, and A1g and its shoulders each represent a different transition metal ion distributed in the tetrahedron. For the sample of Ni0.5Zn0.5Fe2O4, it can be observed that when the A1g peak is relatively wide, the MCD signal changes, and the Mn0.5Zn0.5Fe2O4 series sample has the same situation.