Synthesis And Characterization Of Bi-substituted Yttrium Garnet Nanoparticles

Bi-YIG nanoparticles with narrow size distribution were prepared. Three methods have been employed to prepare YIG and substituted ones, such as co-precipitation, microemulsion and gelatin-template. To enhance the dispersibility of Bi-YIG nanoparticles in the organic monomer (e.g. MMA), the emulsion-based bottom-up self-assembly (EBS) method was used to modify Bi-YIG nanoparticles. To invest the magneto-optical properties of Bi-YIG, Bi-YIG/PMMA composite was prepared by in-situ bulk polymerization. The composite shows great potential for magneto-optical applications.(1) Yttrium iron garnet (YIG, Y3Fe5O12) was prepared in reverse microemulsion consisting of water, CTAB, octane and n-butanol, and subsequent heating treatment. A contrastive experiment has been conducted to study the properties of YIG powders prepared by microemulsion and co-precipitation. Particles were characterized by thermal gravity-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. Moreover, the transparency and Faraday rotation of the polymethyl methacrylate slices filled with yttrium iron garnet (YIG/PMMA) were investigated by visible spectrophotometer and Faraday rotation meter, respectively. All results reveal that both of particles prepared by microemulsion and co-precipitation show great potential for magneto-optical applications and the microemulsion-based powders show better properties with respect to particle size and Faraday rotation.(2) Bismuth substituted yttrium iron garnet (Bi-YIG, BixY3-xFe5O12) particles were prepared by co-precipitation using ammonia aqueous solution as precipitant. The influences of surfactants, microwave, and anneal process on the properties of Bi-YIG particles were investigated. Results suggest that Bi-YIG phase transition temperatures and Ms of Bi-YIG particles decrease, the magneto-optical properties of Bi-YIG/PMMA composite increase as the increasing Bi content. Bi-YIG nanoparticles with good magneto-optical properties can be prepared by the addition of surfactant and the irradiation of microwave at the co-precipitation process. Homogenous Bi-YIG nanoparticles were also successfully synthesized by molten-salt method in NaCl-KCl flux at a relatively low temperature (650 oC), and the molten-salt-based powders exhibit better properties than common heat process-based powders, e.g., more homogenized and better particles, lower Ms, lower UV-vis optical absorption and better magneto-optical properties.(3) Bi-substituted yttrium iron garnet (Bi-YIG, Bi1.8Y1.2Fe5O12) particles with homogeneous size have been prepared by a gel-network co-precipitation method using gelatin as template. The influence of gelatin concentration on the properties of Bi-YIG particles was studied, and emulsion-based bottom-up self-assembly (EBS) method was used to modify the prepared Bi-YIG nanoparticles. The obtained products were characterized by XRD, TEM, dynamic light scattering (DLS) and VSM, respectively. Moreover, the transparency and Faraday rotation of Bi-YIG/PMMA composite were investigated by visible spectrophotometer and Faraday rotation meter, respectively. Results show that Bi-YIG particles exihibit better properties as the increasing gelatin concentration, and Bi-YIG particles modified by EBS exhibit better properties with respect to particle size and magneto-optical properties.