| Autor: |
Pedrielli A; European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-Bruno Kessler Foundation) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy. taioli@ectstar.eu.; Laboratory of Bio-Inspired, Bionic, Nano, Meta Materials & Mechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Italy., de Vera P; European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-Bruno Kessler Foundation) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy. taioli@ectstar.eu., Trevisanutto PE; Bruno Kessler Foundation, Trento, Italy., Pugno NM; Laboratory of Bio-Inspired, Bionic, Nano, Meta Materials & Mechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Italy.; School of Engineering and Materials Science, Queen Mary University of London, UK., Garcia-Molina R; Departamento de Física, Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, Spain., Abril I; Departament de Física Aplicada, Universitat d'Alacant, Spain., Taioli S; European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-Bruno Kessler Foundation) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy. taioli@ectstar.eu.; Peter the Great St. Petersburg Polytechnic University, Russia., Dapor M; European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-Bruno Kessler Foundation) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy. taioli@ectstar.eu. |
| Abstrakt: |
Nanomaterials made of cerium oxides CeO 2 and Ce 2 O 3 have a broad range of applications, from catalysts in automotive, industrial or energy operations to promising materials to enhance hadrontherapy effectiveness in oncological treatments. To elucidate the physico-chemical mechanisms involved in these processes, it is of paramount importance to know the electronic excitation spectra of these oxides, which are obtained here through high-accuracy linear-response time-dependent density functional theory calculations. In particular, the macroscopic dielectric response functions of both bulk CeO 2 and Ce 2 O 3 are derived, which compare remarkably well with the available experimental data. These results stress the importance of appropriately accounting for local field effects to model the dielectric function of metal oxides. Furthermore, we reckon the energy loss functions Im(-1/ ) of the materials, including the accurate evaluation of the momentum transfer dispersion from first-principles calculations. In this respect, by using Mermin-type parametrization we are able to model the contribution of different electronic excitations to the dielectric loss function. Finally, from the knowledge of the electron inelastic mean free path, together with the elastic mean free path provided by the relativistic Mott theory, we carry out statistical Monte Carlo (MC) electron transport simulations to reproduce the major features of the reported experimental reflection electron energy loss (REEL) spectra of cerium oxides. The good agreement with REEL experimental data strongly supports our approach based on MC modelling, whose main inputs were obtained using ab initio calculated electronic excitation spectra in a broad range of momentum and energy transfers. |
