Study of the magnetoresistance of sintered (Fe3O4)X(Fe2O3)1-X Ferrite

• Main Authors: Lin, Ming-Hung, 林明宏
• Other Authors: Kuo P.C.
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/54554365865272989972

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 86 === The magnetoresistance properties of pellets of the (Fe3O4)X(Fe2 O3)1-X systems have been investigated. The samples were prepared by reducing the α-Fe2O3 (99.8 %) powder in the mixture of Ar (95 %) and H2 (5 %) atmosphere at 350 ℃. After reducing, the powders were ground and pressed into pellet. The pellets were then sintered in flowing He gas between 1100℃ and 1400℃ for 1 to 12 hours. We found that the samples sintered at 1100 ℃ between 3 and 6 hours and sintered at 1200 ℃ between 1 and 3 hours had better magnetoresistance properties. After sintering at 1100 ℃ for 3 hours, the MR ratio of the samples increases rapidly from 2.5 % for X=0.185 to 4 % for X=0.4, then increase slowly with X to 5 % for X=0.95. From the observation of X-Ray diffraction, the temperature dependence of the resistivity ρ(T), and the I-V curves, we found that the magnetoresistance properties of the (Fe3O4)X(Fe2 O3)1-X systems is belong to the spin dependent tunneling mechanism.