Síntese e caracterização de nanocristais semicondutores magnéticos diluídos de Bi2Te3 e Bi2-xMnxTe3 em matrizes vítreas

Abstract

In this dissertation, we present results of synthesis Bi2Te3 and Bi2-xMnxTe3 nanocrystals in glass matrix. To confirm the formation of these nanocrystals, experimental measurements were performed of Differential Thermal Analysis, X-ray diffraction, Magnetic Force Microscopy, Transmission Electron Microscopy and Electron Paramagnetic Resonance. The diffraction peaks Bi2-xMnxTe3 nanocrystals move to larger angles with the increased Mn concentration due the change of lattice parameter in the crystalline structure characteristics of Bi2Te3, providing strong evidence for incorporation of Mn2+ ions in the crystal structure of Bi2Te3 nanocrystals. Electron Paramagnetic Resonance spectra corresponding to the electronic transition 1 2 1 2 + ↔ − show the six hyperfine lines characterized by Mn2+ ions when incorporated into Bi2Te3 nanocrystals, showing the signal of types SI and SII, characteristic of Mn2+ ions incorporated in the interior and in the nanocrystal surface, respectively. Electron Microscopy Transmission and Magnetic Force Microscopy images, obtained for the glass matrix 45SiO2.30Na2CO3.5Al2O3.20B2O3 (mol%) + 2 Bi2O3+ 2Te (%wt) + xMn (%wt (Bi)) confirmed the growth of Bi2-xMnxTe3 nanocrystals.