밀리미터파 흡수용 소재로서 입실론 산화철 나노 분말 제조

Abstract

we developed a simple and commercially applicable method for the fabrication of high-purity epsilon-iron oxide(ε-Fe2O3) nanoparticles via spray drying process combined with post heat treatment in the air. The resulting iron oxides showed high-purity ε-phase(~100 wt%) and a magnetic field of approximately 22 kOe at room temperature. This process forms a mixed precursor powders thorough rapid evaporation of the precursor solution. During post heat treatment, silica in the solid microsphere induces the physical limitation of precursor salts, resulting in γ-ε-a route of phase transformation of iron oxide. This yields higher than methods using reverse-micelle&sol-gel or impregnation of mesoporous templets. Magnetic materials with large coercive field can absorb the high-frequency electromagnetic waves by ferromagnetic resonance. ε-Fe2O3 with a coercive field of 20 kOe at room temperatrue shows ferromagnetic resonance at about 180 GHz. For practical application, a lower frequency region (10~100 GHz) absorbing material was required. Thus, we adjusted the coercive field by replacing non-magnetic elements with Fe3+ of ε-Fe2O3, resuling in tunable frequencies from 70 to 110 GHz.