Structural, Optical, and Ferroelectric Behaviors of Cu1−x Li x O (0 ≤ x ≤ 0.09) Nanostructures

Abstract

We report structural, optical, and ferroelectric behaviors of lithium-doped copper oxide (Cu1−x Li x O with x = 0.0, 0.05, 0.07, and 0.09) nanostructures synthesized by hydrothermal method. The XRD pattern indicates the pure phase formation of CuO without any impurity, and the crystallite size is found to be increases for x = 0–0.07 and decreases for x = 0.09. FESEM analysis shows that the average size of Cu1−x Li x O nanostructures increases with the increasing the Li-doping concentrations up to 7% and then decreases for 9% Li doping concentration. Moreover, Raman and photoluminescence spectrum also confirm the phase formation of CuO. A significant reduction in optical band gap is observed up to x = 0.07, and then band gap increases for x = 0.09 due to segregation of the impurities on the surface or grain boundaries, which may suppress the grain growth and results the enhancement in optical band gap. Moreover, a weak ferroelectricity is observed in CuO nanostructures for pure and 9% Li doping through polarization versus electric field (P–E).