Incorporação de Mn no óxido semicondutor magnético diluído ZnO via síntese química: método pechini.

Abstract

Wurtzite-type ZnO doped with transition metal (MT), as a diluted magnetic semiconductor, has great potential in applications in the spintronic. Evidence has been gathering from several studies that the magnetic properties in Zn1-xMTxO system are closed related to the presence of the dopant in the lattice, structural defects and presence of vacancy (oxygen or zinc). Generally, structural defects and presence of vacancy are attributed to the substitution of the Zn atom by MT and to the sample preparation process. However, the room-temperature ferromagnetism in these samples is still controversial. There is still a lot of research on the subject. To study the magnetic properties of these systems are required samples with detailed structural characterization. In summary, the control of the composition, morphology, crystalline quality and particle size is very important to obtain the samples. The Pechini method is a chemistry route of synthesis widely used for the preparation of oxides. The method is known for advantages such as mixtures at the molecular level of the reagents, homogeneity in ion distribution, samples obtained at low temperature, low cost, particle size control and other technical characteristics. In this context we used this chemical route to obtain samples of the Zn1-xMnxO system (with the concentration varying from 1 to 8% Mn). Samples were obtained after heat treatment in argon and air atmosphere at temperatures between 500 and 1200°C. The results of X-ray powder diffraction (XRDD), Raman scattering and X-ray absorption (XANES / EXAFS) measurements indicated samples, in powder form, free from secondary phases at concentrations up to 6% Mn. Scanning electron microscopy (SEM) measurements were used to analyze particle size and morphology of the powders. The percentages of the atomic constituents of the material (chemical composition of the samples) were determined by Energy-dispersive X-ray spectroscopy (EDS) measurements.