Fabrication of MgO-Y2O3 Composite Nanopowders by Combining Hydrothermal and Seeding Methods

In this study, the combination of hydrothermal technique and seed-doping method was conducted to coordinately control the formation of fine MgO-Y2O3 powders, which are promising mid-infrared materials applied to hypersonic aircraft windows due to their excellent infrared transmissions over wide regions. Y(NO3)3·6H2O, Mg(NO3)2·6H2O, Y2O3 seeds and MgO seeds were used as raw materials to prepare the MgO-Y2O3 composite powders (50:50 vol.%), and the influences of the seed contents and hydrothermal treatment temperatures on the final powders and hot-pressed ceramics were investigated by XRD, SEM and TEM techniques. The results show that powders with a seed content of 5% that are hydrothermally synthesized at 190 °C can present a better uniformity and dispersion with a particle size of ~125 nm. Furthermore, the ceramics prepared with the above powders displayed a homogenous two-phase microstructure, fewer pores and a fine grain size with Y2O3 of ~1 µm and MgO of ~620 nm. The present study may open an avenue for developing transparent ceramics based on MgO-Y2O3 nanopowders prepared by hydrothermal technique.