Experimental details
Synthesis
Zinc acetate (Zn(CH3COO)22H2O), SLS (C12H25O4SNa), Cobalt ni-trate (Co(NO3)2) and Sodium hydroxide (NaOH)are purchase d from Merck Chemicals. All of the chemical reagents used in this experime nt are analytical grade and used without further purifica-tion. The procedure employed for preparin g ZnO nanopowders is as follows. In a typical synthesis, zinc acetate (2.195g, 0.01mol%) was grounded for 5min and SLS (2.018g, 0.007 mol%)was added to zinc acetate. After the mixture was grounded for another 5 min, it is stood for 2hat room temperature . The mixture that is
still a solid powder was then mixed with sodium hydroxide pellets (0.89 g, 0.02 mol%)and grounded again for 30 minutes. Later 0.03 mol% of cobalt nitrate is added to the above mixture. The product is washed several times in an ultrasonic bath with distilled water and alcohol (till the pH of solution becomes neutral)to remove any by-product and SLS. After washing, the solution is centri-fuged at 10,000 rotations per minute (rpm)about 30 minutes. The settled powder is collected and dried in air at 80 C for 2h.