Nanocrystals modeling by QHRTEM advanced techniques

Abstract

This project aims the development and application of advanced techniques of Quantitative High-Resolution Transmission Electron Microscopy (HRQTEM) by the analysis of gadolinium-doped ceria (CGO) samples, material correlated to many technological issues, especially Solid-state Oxide Fuel Cells (SOFC). The proposed research focuses on evaluating Gadolinium (Gd) and Oxygen Vacancies (O) distribution in nanostructures obtained by two synthesis routes: precipitation at room-temperature and precipitation followed by microwave-based hydrothermal treatment. These chemical routes allow the achievement of spherical nanoparticles and nanorods, respectively. Gadolinium spatial distribution evaluation at atomic scale will be performed by atomic number contrast technique (Z-contrast) associated to High-Resolution Scanning Transmission Electron Microscopy (HRSTEM). Oxygen vacancies distribution will be analyzed by focal series reconstruction of exit wave function (Software Cs-corrected HRTEM), that allows the evaluation of phase images with improved spatial resolution due to the correction of spherical aberration. Complementary measurements for Oxygen vacancies distribution will be performed by focal series of images obtained by Hardware Cs-corrected HRTEM. This technique allows imaging with optimum conditions of spherical aberration and focus by using a system based in electromagnetic multipoles, resulting in images with outstanding point resolution and contrast. In these terms, the main objectives of the proposed research are the national development of advanced techniques in HRQTEM and the atomic mapping of CGO, focusing a better structural comprehension of this promising material on the development of clean energy sources. By accomplishing these two objectives it is expected to contribute to the improvement of CGO catalytic properties through the better understanding of the interdependence among the characteristics that will be investigated and the ionic transport efficiency. (AU)