Investigation by EPR of defects in polycrystalline samples of BiMn2O5

• Grant number: 12/13971-1
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: September 20, 2012
• End date: November 19, 2012
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Lygia Christina de Moura Walmsley
• Grantee: Vinicius Tadeu Santana
• Supervisor: Rüdiger-A. Eichel
• Host Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Institution abroad: Karlsruhe Institute of Technology (KIT), Germany
• Associated to the scholarship: 10/12790-8 - Electron spin resonance (ESR) in plastdoped polyanilines and AC conductivity and ESR in oxides., BP.MS

Abstract

In our master's studies, we have been investigating the electric and magnetic behavior of double perovskites through ac conductivity and the polaronic defect structure of doped polianilines through Electron Spin Resonance (EPR). Another interesting kind of defects which can be studied through EPR spectroscopy is that due to oxygen vacancies in oxide materials. Multiferroics are a very interesting class of materials which combines both ferroelectric and magnetic properties. The study of dipole defects, its formation mechanism, and its influence on the dielectric and magnetic properties in multiferroic perovskites, such as RMn2O5 (R=rare earth or Bi), is very important to establish their potentialities of applications and contribute to the understanding of the ferroelectric and antiferromagnetic behavior. In this work, we will study Electron Paramagnetic Resonance (EPR) spectroscopy in the context of the defect structure of BiMn2O5 which has shown interesting electrical properties possibly related to those defects. If defect complexes of oxygen vacancies and acceptors are formed, we can have Mn2+ or impurities that can be seen through EPR spectroscopy. Mn4+ and Mn3+ are also possible contributions to EPR line with superexchange interaction among them through the oxygen atoms. (AU)