Estudos espectroscópicos de vidros nióbio-fosfatos de ferro

Abstract

Iron niobophosphate-glasses [0,1Nb205:0,4P205:0,5Li,0]:yFe2 03 (y = 0; 0,1; 0,2; 0,3; 0,4; 0,5) were prepared in air using the melt quenching technique. The samples were studied using x-ray powder diffraction, infrared spectroscopy, Mdssbauer spectroscopy, thermally stimulated currents (TSDC) and dc conductivity in order to investigate the effect of the increasing concentration of α-Fe203 in the glass matrix. High spin Fe3+ and high spin Fe2+ at the distorted octahedral sites (Fe06) are present in all samples. Cristalline phases of LiFePO4 and α-Fe203 are present for high iron content samples (y = 0,4; 0,5). The dc conductivity depends on the ratio Fe2+/(Fe3++ Fe2+). Variation of two orders of magnitude in the conductivity was observed in the samples under study.