Preparation And Magnetic Studies Of YIG(Y₃Fe₅O₁₂) Nanocrys Powders By Sol-gel Method

Garnet is an excellent magneto-optical material; it has a low near infraredabsorption, and a good Faraday rotation effect. YIG (Y₃Fe₅0₁₂) is a typical garnet-typeferrite with a good Faraday Effect among many materials with garnet structure in nature.Compare to the magneto-optical glass in the early days, YIG has the excellent feature ofgood magneto-optical effect, small saturation magnetic field, better homogeneity andstability. Because of the non-magnetic particles of Y3+, YIG is considered to be arelatively simple material from the magnetic view, so it has also become the basis ofother garnet material study. Current, in addition to the requirements of excellentcomprehensive performance and, more importantly, the YIG ferrite materials should havea mature and ultrapure ultrafine preparation technology. In recent years, with the rapiddevelopment of synthesis technology, many new synthetic approaches ofhigh-performance YIG materials continue to emerge.Nanocrystalline YIG powders were successfully synthesized by the sol–gel methodat a low temperature. Y2O3, HNO3,Fe (NO3)39H2O and citric acid were used as rawmaterials to synthesis YIG nanopowders. By the experiments, we obtained the followingconclusions:1) In the XRD patterns, the powders without calcination had no any obvious diffractionpeak, so it can be judged that the structure of powders is amorphous. The calcinedpowders had many obvious diffraction peaks, and the diffraction peak angle are ingood agreement with that of standard Y₃Fe₅0₁₂PDF#43-0507, so we can judge thatthe calcined powders are YIG powders.2) The prepared powders with porous structure and many fine holes are puffy, and theshape of powders is similar with a continuous network honeycomb.3) It has a huge difference in magnetization values between the calcined powders and theuncalcined powders, the M-T curves show that the magnetization value of uncalcinedpowders is only1.1emu/g at the room temperature, while the magnetization value ofcalcined powders is up to26.5emu/g.4) The magnetization of YIG nanopowders increases as the amount of Er dopingincreases. The effects of Gd doping on magnetic properties are similar with that of Erdoping for YIG nanopowders.