Effect of Nanostructure-Materials on Optical Properties of Some Rare Earth ions (Eu3+ ,Sm3+&Tb3+) Doped in Silica Matrix

Nanoparticles of CdS incorporated in Rare Earth doped silica xerogel (RE3+:SiO2) matrix have been prepared by sol-gel method to study its various aspect. The prepared materials have been characterized by physical and optical technique, such as XRD, SEM, TEM and Photoluminescence (PL). We can conclude from TEM that the particle size of the materials 8 nm and an average particle dimension of 5 nm. It is also found consistent with the theoretical calculation performed based on the Scherrer equation and effective mass approximation (EMA) model. The optical properties of these materials depend on various parameters such as dimension and surface characteristics, doping and interaction with the surrounding environment. Enhancements of Rare Earth (RE) ions luminescence have been observed with the presence of CdS NPs in RE3+:SiO2 matrix. A twenty time more intense dominating orange peaks (616 nm) from the characteristic peak of Eu3+ ions are observed for CdS/Eu3+:SiO2 matrix compared to the sample without CdS NPs. The efficient energy transfer (ET) from CdS NPs to RE ions is primarily responsible for this boost in the luminescence intensity. The emission intensity in PL spectra decreases with raise in the concentration of CdS NPs. With an increase in CdS NPs concentration in RE3+:SiO2 matrix, the emission intensity decreases possibly due to the increase in the concentration of “oxygen vacancy ”and “Si hanging” in the matrix of the silica xerogel. Thus, photoluminescence properties of the material are greatly influenced by site symmetry and hence the concentration of dopant ions.

Keywords: Luminescence, Nanoparticles, Quenching, Radiative parameters, Site symmetry, Sol-gel.