PLASMA-SOLUTION SYNTHESIS OF ZINC OXIDE DOPED WITH CADMIUM

In this work, the process of formation of insoluble zinc and cadmium compounds, initiated by the action of a direct current discharge of atmospheric pressure in air on an aqueous solution of zinc and cadmium nitrates, has been investigated. It was found that when the solution is the anode, the action of the discharge leads to the formation of a colloidal solution of zinc and cadmium hydroxynitrates and hydroxides of white color. The kinetics of the formation of colloidal particles was investigated by the turbidimetric method. It turned out that the rate of formation increases with an increase in the discharge current from 30 to 70 mA. At concentrations of zinc and cadmium nitrates 50 mmol/l the rate constant of the process increases from 1.3.10(-3) to 12.10(-3) s(-1). When this solution is destroyed a precipitate of the corresponding compounds is formed. X-ray analysis showed that the precipitate particles have a crystalline structure. The sediment particles, as shown by SEM, have a spheroidal shape with a characteristic size of about 1 mu m. Thermal decomposition of the resulting precipitate proceeds in several stages and ends at a temperature of similar to 300 degrees C. As a result of calcination, a mixture of crystalline zinc and cadmium oxides is formed According to EDX data, at a molar ratio of 1:1 of zinc and cadmium in the initial solution, the obtained solid particles contain 8 mol.% cadmium and 92% zinc.

Automated summary

The process of forming insoluble zinc and cadmium compounds through direct current discharge in aqueous solutions of zinc and cadmium nitrates was investigated. A colloidal solution of zinc and cadmium hydroxynitrates and hydroxides was formed when the solution acted as the anode. The formation rate of colloidal particles increased with higher discharge current. The resulting precipitate consisted of crystalline zinc and cadmium oxides after thermal decomposition.