Time resolved in-situ X-ray absorption spectroscopy: new perspectives in the study of semiconductors with promising physico-chemical properties

M. E. SALETA; S. J. A. FIGUEROA; D. TOBIA; RODOLFO SÁNCHEZ

Virtual

Congreso; 30th Annual Users Meeting (RAU) LNLS/CNPEM; 2020

XANES studies, performed at XAFS2 beamline, reveal that Cr(2-x)TixO3 (x=0.2 - CTO) particles present Ti ions in the +3 & +4 oxidation state. Even more, XPS shown that the Ti ions located at the surface of the CTO are in the +4 state. The resistance (R) of CTO is modeled by small polarons hopping (SPH). R-curve presents a change in the activation energy associated with a variation in the conduction mechanism (750-790 K). This change is not observed in the magnetic and structural characterization. The intensity of selected peaks of the Ti K-edge XANES spectra as a function of temperature exhibits a break as occurred in the R-curve. This change is associated with variations in the electron-phonon interaction. The Ti ions in the particle lead to SPH between the transition metal sites. [1] In addition, the CTO was evaluated as acetone vapor sensor. In-situ XANES experiments shown that the CTO changes its spectra with the incorporation of the vapor. [2]The configuration of the new QUATI beamline will allow us to improve the previous experiment, performing EXAFS with better time resolution (