Inovação no crescimento de nanocristais de CdS e Cd1-xCrxS com vidro reciclado como alternativa sustentável à matriz SNAB

Abstract

In this work, CdS and Cd₁₋ₓCrₓS nanocrystals (NCs) were successfully synthesized and grown in the SNAB glass matrix, with a nominal composition of 40SiO₂ · 30Na₂CO₃ · 1Al₂O₃ · 29B₂O₃ (mol%), doped with CdS and Cr₂O₃, using the melt- quenching method. Additionally, CdS NCs were grown in an alternative system, the Heineken beer bottle glass. The properties of these materials were analyzed by Optical Absorption (OA), Photoluminescence (PL), Raman Scattering (RS), and Electron Paramagnetic Resonance (EPR). Through the OA spectra, it was possible to identify the absorption band of CdS NCs and the characteristic transitions of Cr²⁺ and Cr³⁺ ions in the visible range. The Crystal Field Theory (CFT), applied to the OA spectra, confirmed the tetrahedral (Tt) and octahedral (Oc) coordination sites of Cr²⁺ (3d⁴) / Cr³⁺ (3d³) ions in Cd1-xCrxS NCs. The PL spectra showed that the increase in Cr doping suppresses the emissions from CdS NCs, with Cr²⁺ and Cr³⁺ transitions prevailing. This indicates an energy transfer from CdS NCs to Cr²⁺/Cr³⁺ ions in the SNAB matrix, in addition to the formation of CrO (Cr²⁺) and Cr₂O₃ (Cr³⁺). In the alternative glass system (Heineken), the energy transfer occurs in the opposite direction, from Cr³⁺ to CdS NCs. The EPR spectra confirm the valence of Cr³⁺ ions. The resonant signals and g factor result from the distorted octahedral coordination of Cr³⁺ ions in CdS NCs and the SNAB glass matrix.The Raman spectra reinforce the evidence of the growth of Cd₁₋ₓCrₓS, CrO, and Cr₂O₃ nanocrystals in the SNAB matrix, due to the presence of their typical vibrational modes. In the alternative glass system (Heineken), the Raman spectra identify a soda-lime-silica glass with the Cr³⁺.