The role of Y on the structural, magnetic and optical properties of Fe-doped ZnO nanoparticles synthesized by sol gel method

In this work, we have studied the role of Y ions on the structural, magnetic and optical properties of Fe-doped ZnO nanoparticles synthesized by the sol gel method. Rietveld refinement confirmed the single phase of ZnO, without any secondary phase. The lattice parameters and the lattice strain increased, while the crystallite size decreases with increasing of dopant concentration. Fourier transform infrared analysis showed the characteristic absorption bands of ZnO, with some changes in the intensities. The micrographs showed particles with irregular shapes and increase of the agglomerates. The role of Y on the magnetic properties of Fe-doped ZnO nanoparticles was also analyzed. The magnetic measurements at 300 K exhibited a diamagnetic behavior for undoped ZnO sample and doped with Y. A magnetic transition was verified for co-doped samples, now with a ferromagnetic (FM) contribution in combination with a paramagnetic component. The FM exchange mechanisms involving intrinsic defects are the main cause of ferromagnetic behavior. Photoluminescence spectra showed asymmetric shape and confirmed the magnetic phase transitions with the presence of peaks associated with different defects states. The optical band gap values are explained as stronger sp-d exchange interaction between the band electrons of ZnO and the localized d electrons of the Y and Fe ions substituting for Zn ions. This work contributes to the understanding the role of Y on different properties of Fe-doped ZnO nanoparticles, which may be important for future applications.