Advances in Materials Physics and Chemistry, 2015, 5, 344-349 Published Online August 2015 in SciRes. http://www.scirp.org/journal/ampc http://dx.doi.org/10.4236/ampc.2015.58034 How to cite this paper: Dai, M. and Pu, S.L. (2015) Synthesis and Faraday Effect of Fe-Al Oxide Composite Ferrofluid. Ad- vances in Materials Physics and Chemistry, 5, 344-349. http://dx.doi.org/10.4236/ampc.2015.58034 Synthesis and Faraday Effect of Fe-Al Oxide Composite Ferrofluid Min Dai 1,2 , Shengli Pu 2 1 College of Mining, University of Guizhou for Project and Application Technology, Guizhou, China 2 College of Science, University of Shanghai for Science and Technology, Shanghai, China Email: daiminshh@aliyun.com Received 24 July 2015; accepted 24 August 2015; published 27 August 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract A kind of ferrofluid containing Fe-Al oxide composite nanometer particles was synthesized. The ferrofluid made of Fe-Al oxide composite nanometer particles which ratio was Fe:Al 2 O 3 = 3:1 and thermally treated at 300˚C showed Faraday effect approximate linearity versus the magnetic field B, and a relatively excellent Faraday effect without saturation in varying 0 - 1.5T magnetic field, which provided a method for synthesizing the ferrofluid of Faraday rotation still continuing in a relatively high magnetic field. Keywords Faraday Effects, Ferrofluid, Fe-Al Oxide Composite Nanometer particles, Saturation 1. Introduction Faraday effect is the rotation of polarization plane of the linearly polarized light due to magnetic field induced circular birefringence of a material, which depends on the incident light wavelength and the structure of the ma- terial. The rotation angle θ = π(Δn/λ)L, where Δn is the index difference between the left and right circularly polarized light, λ is the wavelength of the incident light and L is the length of the sample along magnetic field direction. Faraday active materials are often used to fabricate many optical devices and sensors, such as optical isolators [1], optical information storage devices [2], and highly sensitive magnetic field sensors [3] [4]. Mea- surements of Faraday effect have also been used to determine the electron concentration and its profile in semi- conductors where the effective mass of the carrier is known [5]. Researchers continue to discover and synthesize new Faraday active materials to expect more extensive applications of Faraday effects in many areas. At present, researchers have synthesized a lot of films, glasses and crystals with Faraday effects [6]-[9]. Synthesizing vari- ous new nanometer materials with excellent Faraday effects is ongoing.