Influência de nanopartículas metálicas e semicondutoras em vidros dopados com terras-raras para aplicações fotônicas

Abstract

Glass is a fascinating material and it has been used by man in many ways during the history of mankind, from cutting artifacts made of natural glass in the prehistoric age up to optical fibers for telecommunications and solid-state laser today. The rare-earth elements have unique characteristics in the orbital and electronic transitions that allow the use of these elements as emitting electromagnetic radiation in a wide range of the spectrum, ranging from ultraviolet to infrared. By reducing the size of systems to the nanometer range one obtains distinct properties and effects due to quantization, the understanding and application on how these new effects have attracted much attention. Glasses, rare-earths and nanostructures already represent a separate challenge in the characterization and understanding of physical phenomena presented, as well as potential technological applications. The aim of this work is to study the interactions that occur when joining the three systems, ie, to determine the interaction between metal and semiconductor nanoparticles with rare-earth ions in glassy matrices. The systems studied are glassy silicates doped with rare-earth ions erbium (Er3+) and neodymium (Nd3+) and nanoparticles of silver (Ag) and cadmium sulfide (CdS). The samples were prepared by the fusion method followed by rapid cooling, and some samples had undergone heat treatment process for the nucleation and growth of nanoparticles. The characterization of the samples was done using the techniques of optical absorption (AO), photoluminescence (FL) and time-resolved photoluminescence (FLRT) focusing on the transition from 1.5 µm to Er3+ and 1.06 µm to Nd3+. In the data analysis it was used the Judd-Ofelt theory for rare-earth ions, the Mie theory for metal nanoparticles, and the theory of quantum confinement for the semiconductor nanoparticles. The results demonstrate the energy transfer from CdS nanoparticles to the Nd3+ ions in a radioactive and increased quantum efficiency of Er3+ ions in the presence of Ag nanoparticles.