Study of vapors sensing materials employing rapid acquisition of total scattering experiments analyzed by the atomic pair distribution function method at Jatobá beamline

MARTÍN E. SALETA; DINA TOBIA; RODOLFO SÁNCHEZ

Congreso; 31Annual Users Meeting LNLS (RAU 2021); 2021

LNLS - CNPEM

Atomic pair distribution function (PDF) is an attractive technique toanalyze X-ray total scattering data. PDF is a powerful characterization tool inmaterial science, and it is an alternative /or complement to conventional X-raydiffraction (XRD) and X-ray absorption spectroscopy. Contrary to XRD that onlyreflects information about the average structure, PDF analysis allows thedetection of small local distortions [1], bringing information of the local andmedium-range order. This method has also been used to study amorphous phases ofmaterials, i.e., those presenting XRD patterns containing broad andlow-intensity Bragg peaks. Additionally, it has been useful in structuralstudies of nanomaterials in which their characteristic sizes limit the properstudy by conventional XRD [1]. PDF helps to answer a series of questionsregarding local structure, nano-phase detection and quantification [2], andelucidate anion redox or sensing reactions [3]. The first PDF experimentperformed at LNLS was measured at the XDS beamline studying ferroelectic materialswith perovskite structure [4].The followingcharacteristics are mandatory to perform total scattering experiments to beinterpreted by PDF: (i) reach highmomentum transfer (Q), preferablyhigher than 20 Å-1; (ii)obtain high resolution in Q and goodstatistics (high signal-to-noise ratio) for high Q-values; and finally, (iii)use instruments with low background noise, since the data need to have a bettersignal-to-noise ratio than for Rietveld refinement [1]. The projected beamline,Jatobá, will satisfy all these characteristics. It would reach energy values upto 71 keV, that it is reflected in a Qmax of 37 Å-1 at the2D detector.Wepropose to analyze by PDF nanostructures of (Cr,Ti)2O3 as a function oftemperature and at different atmospheres. With this experiment we expect toelucidate if the surface if affected with the external parameters (temperatureand atmosphere) producing nanocluster with distorted structure. [1] T. Egami &S.  Billinge, ?Underneath the Braggpeaks: structural analysis of complex materials. Pergamon, 2003.[2] M.E. Saleta et al., ?Localstructure on BaFe2As2: formation of nanotwins studied byatomic pair distribution function?, 27th Annual Users? Meeting LNLS (RAU),Campinas ? Brazil, November 2017.[3] Zhu H. et al., ?ANew Insight into Cross-Sensitivity to Humidity of SnO2 Sensor? Small14 (2018),1703974[4] M.E. Saleta, et al., ?Atomic pair distribution function at theBrazilian Synchrotron Light Laboratory: application to the Pb1?xLaxZr0.40Ti0.60O3ferroelectric system?,  J. Synch. Rad. 24(2017), 1098?1104.