Size induced structural modifications in copper oxide nanoparticles synthesized via laser ablation in liquids

Laser induced breakdown at copper-water interface is employed to synthesize copper oxide nanoparticles. Copper forms two stable oxides: monoclinic CuO and cubic Cu(2)O. The characteristic traits of laser induced plasma at copper-water interface are altered to analyze the size induced structural modifications in these oxides. The properties of laser produced plasma were varied by changing the focusing conditions of the source laser. Tightly focused condition led to formation of CuO of size <= 200 nm whereas laser defocusing condition produces nanocolloids of Cu(2)O of size less than 10 nm. These findings were attributed to high pressure (60 GPa) accompanied by high temperature at tightly focused condition which results in growth of covalent CuO whereas lower pressure (1.3 GPa) and low temperature at defocused condition probably forms symmetric Cu(2)O. (C) 2011 American Institute of Physics. [doi:10.1063/1.3626463]