Synthesis of a Magnetic-Dielectric YIG@BaTiO3 Composite via Hydrothermal Processing

Abstract

ABSTRACTYIG@BaTiO3 composite was synthesized by a sequential process involving the formation of TiO2 by sol-gel reaction and a subsequent hydrothermal transformation from TiO2 to BaTiO3. TiO2 layer was coated on YIG particle via sol-gel reaction which comprised hydrolysis and condensation reaction of titanium n-butoxide. The pH value of the solution was precisely controlled to ensure that YIG particles could be well dispersed in the solution and the concentrations of TBOT and H2O were adjusted to obtain variant thickness of TiO2 layer. Nano-sized BaTiO3 coating on YIG was achieved by a hydrothermal conversion of the TiO2 shell layer. BaTiO3 shell layer was synthesized in an autoclave at 240°C for 12 hours and the concentration ratio of [Ba]/[Ti] was 1.6. Phases and morphology of the composite are identified by X-ray diffraction and SEM, respectively. Magnetic properties of YIG@BaTiO3 composite were investigated by vibrating sample magnetometer. Coercivity of YIG@BaTiO3 composites with different composition were not affected but the saturated magnetization dropped down with increasing of the volume ratio of BaTiO3. Permittivity of YIG was raised by coating of BaTiO3 layer and was varied from 6 to 60 and 75 by tuning up the volume ratio of BaTiO3 in the composite. The mechanism of the formation of YIG@BaTiO3 composite was also discussed in the article.