Growth conditions for zincite zinc oxide nanocrystallites in aqueous solutions by microwave hydrothermal process

Abstract

Zincite zinc oxide (ZnO) nanocrystallites have been prepared successfully by a novel microwave hydrothermal (M-H) process in an MDS-6 microwave hydrothermal system respectively under temperature controlled mode and pressure controlled mode using zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and sodium hydroxide (NaOH) as raw materials. The influences, such as hydrothermal temperature, zinc ion concentration ([Zn2+]), autoclave filling ratio, reaction time at designated hydrothermal temperature under temperature controlled mode, and hydrothermal pressure, [Zn2+] concentration, autoclave filling ratio, reaction time at designated hydrothermal pressure under pressure controlled mode on the phase compositions and morphologies of ZnO crystallites were particularly investigated. The as prepared ZnO nanocrystallites were characterised using X-ray diffraction, field emission scanning electron microscope and transmission electron microscope. Results show that ZnO nanocrystallites with different morphologies are prepared under specific conditions. A substantial reduction in the reaction time as well as the reaction temperature is also observed compared with the conventional hydrothermal process.