Synthesis and characterization of nickel doped zinc selenide nanospheres for nonlinear optical applications

Phase purity plays an important role in determining the properties of the material and its subsequent applications which depends on the synthesis conditions and dopant concentrations. Phase pure zinc selenide and nickel doped zinc selenide nanoparticles were synthesized by hydrothermal method using sodium selenite as precursor. Calculated crystallite size for various compositions showed a decrease with dopant concentration with the values around 10 nm and less. Morphological analysis showed the formation of spherical particles which is distinct in the micron scale image. SAED pattern showed the formation of nanocrystalline particles with particles size varying between 10 and 20 nm. Quantum confinement effect due to reduced size was corroborated with increased band gap values as measured from diffuse reflectance spectra. Photoluminescence spectra showed the presence of dominant near band-edge emission along with certain defect level emissions for all the samples. Nonlinear optical studies carried out using a continuous wave laser showed an increase in nonlinear refractive index and susceptibility values with dopant concentration signifying the role of defects and the structural modifications occurring due to doping. The nonlinear optical properties exhibited by this material has been utilized for device applications like optical limiting and the results show enhancement in limiting efficiency with dopant concentrations. (C) 2019 Elsevier B.V. All rights reserved.