Influence of Sr concentration on crystal structure, magnetic properties and supercapacitance performance of ZnO nanoparticles

This work reports the synthesis and characterization of Sr doped ZnO nano-needles prepared by the chemical precipitation method. Studying the outcome of Sr doping on crystallite size, microstructure, optical and magnetic properties, synthesized nanoparticles were examined by using an x-ray diffractometer, a vibrating sample magnetometer, an ultraviolet-visible spectrometer, a field emission scanning electron microscope, and a photoluminescence spectrometer. The XRD investigation confirmed the increase in average crystallite size from 16 to 33 nm with the increase in Sr content up to 5% and then decreased to 26.23 for 10% of Sr content. The UV-Vis spectra confirmed the bandgap variation from 3.53 to 3.33 eV with Sr doping. FTIR spectra confirmed the substitution of Sr in ZnO through the slight shift of vibrational bonds at 570 cm(-1) towards the higher wavenumber. UV emission at 395 nm observed in PL spectra confirmed the formation of ZnO nanoparticles. A microstructural analysis established the morphology transformation from nanoflakes to nanoneedles at a higher amount of Sr. Magnetization behaviour confirmed the weak ferromagnetism in undoped and Sr doped ZnO nanoparticles. The saturation magnetization, retentivity, and coercive field of 3% Sr doped ZnO are 0.30 emu g(-1), 0.034 emu g(-1), and 0.064 T, correspondingly. The enhancement of coercivity and magnetization is attributable to the replacement of Zn2+ by Sr ions. A cyclic voltammetry study suggested that Sr doped ZnO nanoflakes may be a promising substantial electrode for supercapacitor development.

Automated summary

In this work, Sr doped ZnO nano-needles were synthesized and characterized. The study showed that the crystallite size increased with the Sr content up to 5% and then decreased. Sr doping also caused a variation in the bandgap. The FTIR spectra confirmed the substitution of Sr in ZnO. PL spectra confirmed the formation of ZnO nanoparticles. The magnetization behavior confirmed the weak ferromagnetism in Sr doped ZnO nanoparticles. Cyclic voltammetry study suggested that Sr doped ZnO nanoflakes could be a promising electrode material for supercapacitor development.