Effect of NaOH molar concentration on morphology, optical and ferroelectric properties of hydrothermally grown CuO nanoplates

Abstract

In this paper, structural, morphology, optical and ferroelectric properties of well uniform rectangular shaped copper oxide nanoplates prepared by hydrothermal technique at different 3, 5 and 6 molar concentrations are reported. X-ray diffraction confirmed that CuO nanoplates have a monoclinic phase with lattice constants a=4.689Å, b=3.426Å, and c=5.132Å. Transmission electron microscope analysis reveals that in CuO nanoplates average length and width increases from 80 and 246 to 115 and 290nm as the molarities concentration increases from 3 to 6M. Selected area electron diffraction patterns confirm that the crystallinity of CuO nanostructures increases with increasing NaOH concentrations. Photoluminescence and Raman spectrum also confirm the phase formation of CuO nanostructures. A significant decrease in optical band gap is found from 3.55 to 2.95eV as molar concentration increases from 3 to 6M, respectively. The refractive index (n), optical static (εo) and high frequency dielectric constant (ε∞) values were calculated through energy band gap as function of molar concentration of NaOH solution. Moreover, room temperature ferroelectricity has been notice in hydrothermally grown CuO nanoplates which are interesting and adds a further dimension to its applications.