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Tungsten cathode materials doped with rare earth oxides has aroused great concern with its low work function, enhanced electron emission capability, low temperature characteristics. Control the tungsten matrix grain size and to improve the degree of rare earth oxides dispersed in the matrix, is the key to improve the characteristics of the electron-emitting ability. To this end, the thesis preparation of tungsten powder doped with rare earth oxide nano technology. The this dissertation System solid - solid, solid - liquid, liquid - liquid three doping ways to restore the former material mixing uniformity, then under reducing conditions in the industry, using materials obtained three doping ways reduction, and the use of x-ray diffraction, scanning electron microscopy analysis means for analysis of the final powder prepared. The study showed that the solid - solid dopant prepared powder, coarse particles, tungsten particles substantially maintain the original form, the particle size to 1 to 4 μm; doping prepared powder particle diameter of the solid - liquid is significantly less than the solid - solid doping prepared has also been significantly improved powder particle size, particle size, the uniformity of most of the particle size of about 1μm; ammonium metatungstate and rare earth nitrate solution as raw material, ion level to achieve uniform mixing of the liquid - liquid doping finally obtained tungsten powder fine, particle size distribution is relatively uniform, and particle size of 500 nm to 1 μm. This paper focuses on liquid - liquid doped → freeze drying → twice to restore the prepared nano tungsten powder process: to metatungstate ammonium (AMT), rare earth nitrate (La (NO 3 ) 3 , Ce (NO 3 ) 3 , Y (NO 3 ) 3 ) and water as raw material, the preparation of the four solution - AMT solution, the [AMT La (NO 3 ) 3 ] solution, [the AMT Ce (NO 3 ) 3 ] solution, the AMT Y (the NO 3 ) 3 ] solution; four solutions were freeze-dried process processing, and corresponding lyophilized powder; thermogravimetric - differential thermal analysis and infrared spectroscopy of the structure and thermal stability of doped and non-doped ammonium metatungstate lyophilized powder measured, and by the reduction process a series of conditions were established ultrafine tungsten powder restored by the ammonium metatungstate lyophilized powder twice the reduction process parameters to 450 ℃ × 1h 700 ° C for 1h. The use of x-ray diffraction, transmission electron microscopy, scanning electron microscopy analysis techniques for analysis and characterization of the tungsten powder, the regular shape of the prepared tungsten particles having a particle size range between 30 ~ 100nm.
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