Estudos das Correlações Microestruturais, Eletrônicas e Ópticas do BaZrO3 Dopado com Terras Raras

Abstract

Materials science is currently seeking a better understanding of the properties physico- chemicals of advanced compounds. The best understanding of structural properties of a material, allows the construction of electronic and optical devices for the more diverse technological applications, such as light emitting diodes, laser transistors, gas sensors and solar cells. This work presents an experimental study on the local and global distortions of the structural and electronic levels of the composite Zirconate of Barium BaZrO3 (BZO) in its pure state and codoped with Rare Earth ions Terbium (Tb) and Ytterbium (Yb), synthesized via the microwave assisted hydrothermal method in the form of ceramic pow- n der. Non pure samples were doped in solid solution with Tb ions and Yb obeying the 2 substitution model generating a Ba1−xTbx Zr1−y YbO3 system, being (x = 1% e y = 1, 2, 4, 8%) in mol. Structural investigation by x-ray diraction demonstrates that the main crystalline phase in all samples is the cubic phase of BZO, with some secondary phases of BaCO3 and KCl. The results of Raman spectroscopy presented vibrational modes as- sociated with secondary structures and distortions in the crystal lattice generated by the presence of dopants in the cubic BZO matrix. The micrographs indicated for samples with high concentrations of dopants, the decrease and the loss of regularity of the crystals. The analysis of x-ray absorption around the edges. of the LII and LIII of the Zirconium acts, showed that through the ratio between the intensities of the edge peaks, the doping ions induce structural distortions in the ZrO6 cluster of the compost. Diuse absorbance spec- tra indicated small changes in band sample gaps. These eects of structural distortions are related to the eects of octahedral crystalline eld present in the compound associa- 3+ 3+ ted with coupling eects spin-orbit in energy levels. Typical Tb and Yb transitions have been identied in the photoluminescence spectra, conrming the presence of dopants in the BZO. This detailed study of structural and electronic processes lays a foundation solid for future studies of technological applications involving pure BZO compound and codoped.