CONTINUOUS MICROWAVE-DRIVEN POLYOL PROCESS FOR SYNTHESIZING YTTERBIUM-DOPED YTTRIA POWDER

摘要

The continuous microwave polyol process is a promising novel approach to the synthesis of metallic and ceramic nanopowders. Current efforts are directed toward synthesizing ytterbia-doped yttria (Yb_2O_3:Y_2O_3) for use as a polycrystalline laser host material. The process involves pumping a mixture of yttrium nitrate and ytterbium nitrate dissolved in hydrated diethylene glycol through a pressurized quartz tube contained in an S-Band waveguide driven by a 2.45 GHz microwave source at powers up to 6 kW. As the solution moves along the waveguide, it absorbs the co-propagating microwave energy and is heated rapidly to a temperature above 200°C causing a reaction to occur. Condensation reactions then form particles with ytterbium-doped yttria crystal structure. The rapid heating and cooling serve to limit the growth of the crystals so that they are on submicron and fairly uniform in size. The production of doped yttria was confirmed by x-ray diffraction.