Microwave-assisted synthesis of nanocrystallite CuO particles and estimation of their microstructural parameters using Williamson–Hall method

The importance of CuO nanoparticles (NPs) is growing day to day because of their unique properties. For the possible application of these NPs in optoelectronics, it is desirable to synthesise the size-controlled CuO NPs and understand their microstructural, optical, and electronic properties. Here, we report the synthesis of CuO particles having nano-crystallites of average sizes in the range of about 8–10 nm using glycerol and copper acetate monohydrate by the microwave synthesis method for varying microwave power. The band gaps of the nano-crystallites have been obtained from the optical absorption studies and are found to be 2.14 eV, 2.12 eV and 2.08 eV for microwave powers of 180 W, 360 W, and 540 W, respectively. The increase of bandgap with a decrease in particle size is mainly due to the quantum confinement effects in small CuO particles. Blue and green photoluminescence (PL) emissions have been observed, and the intensity of these is seen to change for different microwave powers. The changes in PL intensities are argued due to the change in the microstructural properties of the nano-crystallite CuO particles. Detailed systematic analysis of the X-ray diffraction data employing the Williamson–Hall method clearly indicates that there are significant changes in microstructural parameters viz, strain, stress, and the deformation of energy density in the CuO nano-crystallites synthesised for different microwave powers. The observed changes in the microstructural parameters were induced due to the microwaves produced for varied powers. Also, the formation of CuO particles has been confirmed through Raman spectroscopy and X-ray Photoelectron Spectroscopy studies.