XAS Study of CuAl2O4 Ceramic System

XAS technique was used to study changes around Cu atom in the CuAl2O4-Al2O3 system, induced by composition variations. The results showed that for compositions with 30 and 43% of CuO, the Cu atoms presents the same surroundmg of Cu in the CuO oxide (NCu-O=4, RCu-O=1.96 Å). Samples with 20% (doped or undoped) showed significative changes in the Cu nearest neighbors number (NCu-O=3) and in the mean bond length (RCu-O-1.93 Å). The qualitative analysis of the edge region showed that for the 20% of CuO sample, some Cu atoms changes from Cu+2 to Cu+1. This change was more pronounced for the CuO 20% undoped sample

Structural studies in lead germanate glasses: EXAFS and vibrational spectroscopy

The Raman, IR absorption and EXAFS spectra at the Ge K-edge and Pb LIII-edge of eight lead germanate glasses, with general formula xPbO(1-x)GeO2 with x = 0.20, 0.25, 0.33, 0.40, 0.50, 0.53, 0.56 and 0.60, have been measured. The occurrence of [GeO6] units besides [GeO4] could not be deduced unambiguously from the data. The vibrational and EXAFS data agree with a progressive depolymerization of the network. Starting from all Ge atoms linked to four bridging oxygens in GeO2 (x = 0), the number of tetrahedral units with one or two non-bridging oxygens increases with x. At low content, Pb2+ ions act as modifiers in the germanate structure, but to a lesser extent than an equivalent number of alkaline ions. © 1993

Gas sensors data analysis system: A user-friendly interface for fast and reliable response-recovery analysis

International audienc