Chromium doped ZnO nanoparticles for energy storage, gas and humidity sensing and spin based electronic devices applications

Abstract

This work was suggested to study the impact of Cr ions doping on the structural, optical, electrical and magnetic behavior of ZnO nanoparticles (NPs). The Zn1-xCrxO (with 0 ≤ x ≤ 0.14 wt %) samples were fabricated by the co-precipitation technique. The obtained samples were characterized by the X-ray diffraction (XRD) technique, (FTIR) spectroscopy, UV–vis spectrophotometer, Ac measurements and Vibrating Sample Magnetometer (VSM). As a key results of all the mentioned above tools we can be summarized them as following; XRD patterns showed the presence of wurtzite (hexagonal) crystal structure with secondary phase formation in all doped samples. Also, it was found that as Cr ions were increased the particle size showed gradually decreasing in the samples that doped with Cr ions content of (0.06 and 0.1 wt %), while at 0.14 Cr content a slight increase was observed. The FTIR spectroscopy spectra showed the existence of chromium ions in the structure of ZnO nanoparticles. UV–vis spectra showed a red shift in the centers of the absorption bands. The energy band gab was found to be increased from 3.84 to 4.02 eV with increasing Cr content. The dielectric parameters such as, dielectric constant ({varepsilon }^{^{prime}}) and dielectric loss (mathrm{tan}delta), were investigated as a function of frequency and Cr doping content. The results showed increasing values of {varepsilon }^{^{prime}} at lower frequencies especially with high Cr doping content, whereas mathrm{tan}delta gives a higher value for the blank sample at a lower frequencies and decreased as the doping of Cr concentration increased. The ac conductivity (σac) for Cr doping samples showed increasing values, especially the sample of 0.14 wt % Cr concentration. In addition, the Cr doped ZnO nanoparticles exhibited a ferromagnetic behavior at room temperature. All the results obtained from the different techniques were considered promising for different applications i.e. energy storage devices, gas and humidity sensing and spin based electronic devices applications.