MANUFACTURE OF ELECTRON EMISSION AGENT FOR OXIDE CATHODE

PURPOSE:To easily manufacture an oxide cathode electron emission agent having a fine and uniform grain size by dissolving the carbonate of a binary or higher system of alkaline earth metals containing Ba or the like into organic acid for formation into fine droplets, and splashing and instantaneously drying the droplets in the dry air for the precipitation of powder. CONSTITUTION:The powders of BaCO3, CaCO3 and SrCO3 having a particle size of approximately 5mum or less are mixed at the prescribed mole ratio and supplied to the water solution of organic acid (preferably formic acid) for dissolution. After carbonate is completely dissolved, a spray dryer is charged with the water solution, and this solution is sprayed into the dry air at a temperature approximately between 100 deg.C and 200 deg.C, thereby being changed to fine droplets. Then, the droplets are splashed into the dry air and instantaneously dried. Consequently, an oxide cathode electron emission agent formed out of particles having an approximately uniform size and free from impurity contamination can be easily provided.