| Grant number: | 12/11104-9 |
| Support type: | Regular Research Grants |
| Duration: | October 01, 2012 - March 31, 2015 |
| Field of knowledge: | Engineering - Nuclear Engineering - Applications of Radioisotopes |
| Principal researcher: | Artur Wilson Carbonari |
| Grantee: | Artur Wilson Carbonari |
| Home Institution: | Instituto de Pesquisas Energéticas e Nucleares (IPEN). Secretaria de Desenvolvimento Econômico (São Paulo - Estado). São Paulo , SP, Brazil |
| Assoc. researchers: | José Mestnik Filho ; Rajendra Narain Saxena |
Abstract
The main purpose of this project is to use a nuclear technique for an atomic scale investigation of nanostructured materials of high-dielectric-constant semiconductor oxides by means of the measurements of hyperfine interactions (HFI). Pure or mainly metal doped semiconductor oxides present very interesting properties which make them good candidates for be used in technological applications which can have significant impact in several activities. The material to be investigated in this project are metallic oxides with large band-gap such as HfO2, an insulator material suitable for using in the next generations of microprocessors, or CeO2. In these materials, defects such as vacancies or impurities play a fundamental role in defining their properties. In order to carry out the experimental measurements, the perturbed gamma-gamma angular correlation (PAC) spectroscopy will be used. First-principles calculations using density functional theory will also be performed to calculate the hyperfine parameters. Because it is a nuclear technique, PAC has high precision and efficiency to measure local hyperfine fields in an atomic scale. By its nature, PAC spectroscopy is an ideal tool to investigate the atomic origin of phenomena as the influence of defects in the macroscopic properties of materials, the origin and nature of magnetic ordering or the local neighborhood of metallic atoms in the oxide structure. In the measurements of hyperfine interactions, PAC spectroscopy has the advantage over resonance techniques in being independent of temperature once temperature of the sample does not influence the resolution of measurements, which allows measurements at higher temperatures. The objective of this project is to establish preparation methodology for these oxides in order to improve their properties to be used in technological applications. (AU)