YIG Nanoparticles Research Articles

Magneto-optical properties of Bi-YIG nanoparticles/epoxy hybrid materials

Bi-substituted YIG (Bi 1.8 Y 1.2 Fe 5 O 12 ) nanoparticles were prepared by ultrasonic irradiation-assisted coprecipitation and annealing processes. The nanoparticles were dispersed in a plastic epoxy binder with a dispersing agent to induce polymerization by the solidifying agent. The magnetic and magneto-optical properties of the nanoparticles and the Bi-YIG/epoxy hybrid materials were investigated. The particles heat treated at 650 °C show a spherical shape and its size is smaller than 20 nm. The saturation magnetization of the Bi-YIG nanoparticles is 17 emu/g. As the particle content in the hybrid materials increases from 0.01 to 0.20 wt%, both the Faraday rotation (θ F ) and the Verdet constant of the hybrid materials at the wavelength 525 nm increase from 2.4 to 52.8 deg/cm, and from 0.02 × 10 -2 to 2.63 × 10 -2 deg/Oe cm, respectively.

Two modes of linear layer-by-layer growth of nanoparticle--polylectrolyte multilayers and different interactions in the layer-by-layer deposition.

The structure of the multilayer assemblies of yttrium iron garnet nanoparticles (YIG) with polyelectrolytes was investigated with the emphasis on the control of the particle density in the adsorption layers. It was found that the growth of YIG films prepared by the layer-by-layer assembly can occur via two deposition modes: (1) sequential adsorption of densely packed adsorption layers (normal growth mode) and (2) in-plane growth of isolated particle domains (lateral expansion mode). Importantly, the dependence of the optical density on the number of deposition cycles remains linear in both cases. Microscopy results indicate that the origin of the lateral growth is in the interplay of particle/particle and particle/polyelectrolyte interactions rather than in a substrate effect. The lateral expansion mode is a general attribute of the layer-by-layer deposition and can be observed for various aqueous colloids. For the preparation of sophisticated multifunctional assemblies on nanoparticles, the film growth via domain expansion should be avoided, and therefore, one must be able to control the growth pattern. The switch from lateral to normal growth mode can be effected by grafting charged organic groups to YIG nanoparticles. Hydrophobic interactions between the hydrocarbon groups of the modified YIG and polyelectrolyte significantly increase the attractive component of the particle/polyelectrolyte and particle/particle interactions. The films from modified YIG display densely packed nanoparticle layers with a greatly reduced number of defects.

Synthesis of yttrium iron garnet nanoparticlesvia coprecipitation in microemulsion

P. Vaqueiro, M. Arturo López-Quintela and J. Rivas, J. Mater. Chem., 1997, 7, 501 DOI: 10.1039/A605403J