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Research on Broad Band Gap High Curie Point Rare Magnetic Semiconductor Material

Author: LiDongHong
Tutor: ShangGuanWenFeng；YuanJian
School: Shanghai Jiaotong University
Course: Chemical Engineering
Keywords: Diluted magnetic semiconductors Wide band gap Curie temperature TiO2 Transition metal element
CLC: TN304
Type: Master's thesis
Year: 2008
Downloads: 187
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Abstract


In recent years, the diluted magnetic semiconductor (DilutedMagnetic Semiconductors) (DMS) exhibit a unique phenomenon of magnetic ordering much attention , understanding of their unique magnetic involves many fundamental physical problems , at the same time , these unique magnetic implication huge potential applications , and the ability to get high Curie temperature DMS applications . This article hydrothermal prepared transition metal - doped TiO2 powder samples , the process of preparation conditions on the performance of the sample . Were characterized by XRD, TEM and other methods to characterize the structure of the sample , the magnetic properties of the samples were measured using a vibrating sample magnetometer (VSM) , and combined with structural analysis and magnetic behavior of the samples and carried out a preliminary study of the cause of the sample magnetic . The research results show that the showing undoped TiO2 the single anatase structure , the Co ion doped promote samples from anatase to rutile phase transformation is less than 10% , and the solid solubility of Co ions in the TiO2 . The undoped TiO2 no ferromagnetic signal, and Ti1-xCoxO2 (x = 0.01 ~ 0.04) samples at room temperature showed a ferromagnetism , and also has the characteristics of paramagnetic its Curie temperature of more than 300K . Magnetic ion doping concentration, and the temperature of the water and heat and hydrothermal time is an important factor to affect the sample magnetic iron . Co -doped TiO2 research based on further Mn , Fe, Ni - doped TiO2 powder sample preparation process , and the samples were prepared structural analysis and experimental study of the magnetic properties . The results indicate that the magnetic elements are doped samples exhibit ferromagnetism . Similar to the Co doping system , Mn , Fe, Ni ions in solid solution in the TiO2 were less than 10% , while regular morphology of sample particles , good dispersion , the grain size of about 20nm . The different magnetic ion - doped sample in the magnetic field of 1T , since the presence of a paramagnetic component , the sample magnetization is not saturated . For sample ferromagnetic Source , exclude the possibility of the magnetic ion clusters and metal oxide . In this thesis, the hydrothermal method successfully a good TiO2-based diluted magnetic semiconductor materials with high Curie temperature , preparation repeatability .

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