Avaliação do tipo de precursor e da dopagem no sistema Zn1-ₓFeₓO visando a obtenção de semicondutores magnéticos diluídos (SMDs).

Abstract

The objective of this study is to evaluate the influence the type of precursor, source of iron ions, and its concentration in the doping Zn1-xFexO system in order to obtain a product with ferromagnetism at room temperature for use as magnetic semiconductor diluted. For this purpose, it was firstly evaluated the influence of the type of precursor (iron III nitrate, iron sulfate II, iron acetate II) on the structure, morphology, thermal and magnetic properties of Zn1-xFexO system concentration of Fe2+ and Fe3+ ions of 0.4 mol. After that, it was evaluated the effect of concentration of iron III ions ranging from 0.05 to 0.4 mol on the structure and magnetism of Zn1-xFexO system. During the reactions, there were made measurements of temperature and time. The samples were characterized by: X-ray diffraction, chemical analysis by fluorescence X-ray energy dispersive, scanning electron microscopy, with mapping by EDS, particle size analysis, analysis by nitrogen adsorption, vibrating sample magnetometer and thermal gravimetric analysis. The results have shown that the type of precursor influenced directly the structure, morphology and magnetism of the samples and the precursor of iron nitrate III was the one which favored the obtention of the ferromagnetism material monophasic at room temperature. For the doped samples, the XRD spectra showed that the concentrations until 0.20 mol of iron III ions resulted in a monophasic system with ferromagnetic behavior at room temperature, which characterized the formation of a diluted magnetic semiconductor. For the other concentrations, it was observed traces of MnFe2O4 phase and that the exchange interactions between the ionsFe - Fe and possibly the increasing of oxygen vacancy concentration in ZnO network suppressed the ferromagnetic behavior by the competition of ferromagnetic / paramagnetic one. Therefore, it can be concluded that the precursor of iron III nitrate concentration to 0.20 mol was the best condition for obtaining a product with characteristics for use as a dilute magnetic semiconductor using the synthetic technique by combustion.