Invetigation of nanostructured metallic semiconductor oxides in an atomic scale by a nuclear technique and first-principles calculations.

• Grant number: 12/21132-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: February 01, 2013
• End date: January 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Artur Wilson Carbonari
• Grantee: Emiliano Luis Muñoz
• Host Institution: Instituto de Pesquisas Energéticas e Nucleares (IPEN). Secretaria de Desenvolvimento Econômico (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

The main purpose of this project is the atomic scale investigation of nanostructuredmaterials of semiconductor oxides by means of experimental measurements of hyperfineinteractions (HFI) and first-principles calculations. Pure or mainly metal doped semiconductoroxides present very interesting properties which make them good candidates for technologicalapplications which can have significant impact in several activities. Materials to be investigated inthis project are metallic oxides with large band-gap which, when doped with transition metalelements, can enhance or acquire certain properties. Because these properties, semiconductoroxides can be used as gas sensors, as transparent materials for opto-electronic devices, and formdiluted magnetic semiconductors. In these materials, defects such as vacancies or impurities play afundamental role in defining their properties. In order to carry out the experimental measurements,the perturbed gamma-gamma angular correlation (PAC) spectroscopy will be used. Firstprinciplescalculations using the local density approximation will also be used to calculate thehyperfine parameters. Because it is a nuclear technique, PAC has high precision and efficiency tomeasure local hyperfine fields in an atomic scale. By its nature, PAC spectroscopy is an ideal toolto investigate the atomic origin of phenomena as the influence of defects in the macroscopicproperties of materials, the origin and nature of magnetic ordering or the local neighborhood ofmetallic atoms in the oxide structure. In the measurements of hyperfine interactions, PACspectroscopy has the advantage over resonance techniques in being independent of temperatureonce temperature of the sample does not influence the resolution of measurements, which allowsmeasurements at higher temperatures. The main purpose of this project is to understand the role ofimpurities in the electronic properties of such materials and establish a methodology ofpreparation of oxides with enhanced properties in order to be suitable to the technologicalapplications.