电气博士论文论文.docVIP

电气博士论文论文 本文由海洋宝玉贡献 doc文档可能在WAP端浏览体验不佳。建议您优先选择TXT，或下载源文件到本机查看。 A simple synthesis of Fe3O4 powders and their Structure, magnetic and electrical transport properties K.L. Liu*, Y. D. Du, C.Y.Li Department of Physics, Zhenzhou electicl power collage zhang haiyang People’s Republic of China. ABSTRACT Fe3O4 powders with highly crystalline have been synthesized by a sol-gel auto combustion synthesis method accompanying thermal process. The phase structures, morphologies of Fe3O4 have been characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive x-ray spectrometer (EDX). The results show that complete and highly crystalline nature magnetite powders can be obtained. Furthermore, the room-temperature magnetizations and the resistance of Fe3O4 powders were also measured. The maximum magnetization of sample S1, S2and S3 is 88.3, 87.32 and 89.4emu/g at the applied magnetic field 5kOe, respectively, which are larger than the saturation magnetization of the bulk γ-Fe2O3 (76emu/g). It is proved further that Fe3O4 powders can be synthesized by the citrate-nitrate sol-gel auto combustion reaction method. The preliminary reaction mechanism is also discussed. Keywords: Fe3O4; Magnetic materials ; Sol-gel preparation; Half metallic 1. Introduction Magnetite, Fe3O4, is ferromagnetic inverse spinel structure with an anomalous high Curie temperature of 860 K and an exceptionally high conductivity [1]. In addition, the band-structure calculations for magnetite have indicated that Fe3O4 is half-metallic and the conduction electrons * Corresponding author. Address: Department of Physics, Zhoukou Normal University, Zhoukou 466000, PR China. Tel E-mail address:liukuili@163.com 1 are 100% spin polarized [2]. These properties make magnetite to be applied extensively in magnetoresistive devices, magnetic storage and biomedicine [3-7]. The nanocrystalline magnetite with a uniform particle si