抄録
Various solid solutions with corundum, spinel, and rutile structures were synthesized by microwave irradiation at a frequency of 28 GHz. During irradiation, powder samples were rapidly heated, and final product was obtained within 60 min. Lamellar structure resulted from spinodal decomposition was observed by TEM on each product. The modulation cycle was 5 to 20 nm, which can be controlled by reaction conditions such as temperature, time, and the kind and amounts of the dopants. In the TiO2-SnO2 system, the band gap energy decreased with the progress of spinodal decomposition. Rutile based GeO2-SnO2 solid solution, which is hard to obtain at ambient pressure, was also synthesized with high yield (over 95%). In the Fe2O3-Al2O3 based system, the products contains Fe-rich and Al-rich layers. Converting Fe2O3 to Fe3O4, magnetic domain is separated by Al2O3 layer, there seems to achieve higher coercive force (Hc).
