Cr doped ZnO nanostructures: synthesis, electronic structures and magnetic properties

We report an experiment in which we have attempted to dope Cr into ZnO nanostructure as a function of dopant concentration using sol-gel method, followed by controlled thermal annealing with some success. We have also examined the samples thus prepared with scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Near Edge X-ray Absorption Fine Structure (NEXAFS), both theory and experiments, and magnetic measurements. We found that low concentration of Cr can indeed be doped in ZnO and is substitutional, occupying the tetrahedral site. However, upon increasing dopant concentration and annealing temperature, a secondary phase with Cr occupying an octahedral site precipitates out as evident from SEM, XRD and NEXAFS. Ferromagnetism at room temperature was not observed in any samples although at low Cr concentration and 400 째C processing temperature antiferromagnetism can be seen but at higher concentrations or processing temperatures the samples show only paramagnetism.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author