Infrared persistent luminescence in rare earth stannate materials

• Grant number: 18/06863-4
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): July 01, 2018
• Effective date (End): June 30, 2019
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal researcher: Hermi Felinto de Brito
• Grantee: Matheus Salgado de Nichile Saula
• Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Materials that exhibit the phenomenon of persistent luminescence are capable of emitting light for more than 24 hours after a source of radiation has ceased on it. Its long time of emission is explained by the storage of excitation energy in defects of the crystalline network (called traps). This energy is released gradually, with the advent of the thermal energy present in the environment. Near-infrared emitting materials (NIR) have been attracting attention to applications such as bioimaging, photodynamic therapy, and medical diagnostics since they emit in regions of higher transmittance in biological tissues. Although materials with persistent luminescence have been investigated for centuries, emitters of this phenomenon in the NIR region are still scarce, and most of the current materials are expensive because they contain gallium and germanium elements in their composition. In addition, the preparation of this type of material normally demands high temperatures (1200 ° C) and several hours of calcination, adding even more costs to the production. In this context, the microwave-assisted solid state synthesis methodology (MASS) has drawn attention because, due to a punctual dielectric heating, it allows to obtain materials with a high degree of purity in approximately 30 minutes. On the other hand, chemical solvent routes, such as the hydrothermal method, allow the synthesis of materials at the nanoscale, allowing in vivo applications. Therefore, the research project proposes the development of Li1,6M1,6Sn2,8O8: R3 + (M2 +: Mg, Zn and Cd; R3 +: Cr, Nd, Yb) materials that present persistent luminescence in the NIR region, and carry out the study of their photoluminescent properties to elucidate the mechanisms of persistent luminescence, aiming applications in the biological area. (AU)