Influence of silver and gold nanoparticles on the characteristics of dysprosium-activated lithium strontium-zinc-borate glasses
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Date
2021
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Universiti Teknologi Malaysia
Abstract
Silver (Ag) and gold (Au) nanoparticles (NPs) sensitized dysprosium-activated lithium-strontium-zinc-borate glasses are useful in the development of material for solid-state lasers, white light generation, and radiation dosimetry. Therefore, this glass system needs systematic characterizations and accurate composition optimization. Accordingly, series of glasses with molar composition of ??Li2CO3–5SrO–5ZnO–(90-??)B2O3 (10=??=40 mol%), 20Li2CO3–5SrO–5ZnO–(70-??)B2O3–??Dy2O3 (0=??=1.25 mol%), 20Li2CO3–5SrO–5ZnO–(69-??)B2O3–1Dy2O3–??AgCl (0=??=0.9 mol%) and 20Li2CO3 –5SrO–5ZnO–(69-??)B2O3–1Dy2O3–??Au (0=??=0.7 mol%) were developed via conventional melt quenching process. These glasses were characterized via different measurements to determine the sensitiveness of varying Dy3+ doping concentrations and the influence of embedding different concentrations of silver and gold nanoparticles (Ag and Au NPs) on their thermal, structural, physical, and optical characteristics. The Differential Thermal Analysis (DTA) results of the prepared glasses revealed excellent thermal stability and glass-forming ability. The X-ray Diffraction (XRD) analysis of the glasses confirmed their amorphous nature. Fourier Transform Infra-Red (FTIR) and Raman spectra exhibited the presence of BO3 and BO4 functional groups. Energy Dispersive X-ray (EDX) analysis confirmed the presence and homogeneous distribution of traced elements in the glasses. High Resolution-Transmission Electron Microscope (HR-TEM) images demonstrated the nucleation and distribution of Ag and Au NPs in the glass samples. The absorption spectra of the glass materials are consistent with Dy3+ electronic transitions from the ground state to various excited levels. The photoluminescence emission spectra of the glasses exhibited three bands in the visible light region owing to the transition from 4F9/2 to 6H15/2, 6H13/2, and 6H11/2 states. Photoluminescence emission of the Ag and Au NPs dependent glasses exhibited significant intensity where glasses with Au NPs show better enhancement. CIE colour adaptation revealed CCT value in the cool white light region with remarkable improvement of colour purity from 0.037 to 0.103% and 0.078 to 0.156 % for Ag and Au NPs dependent glasses against that of 4.8 to 11.6% for Dy3+ dependent glass samples, better colour purity is observed for glasses with Ag NPs. This demonstrates the usefulness of the materials in the development of white Light Emitting Diode (LED). The Judd-Ofelt intensity parameters indicated an increase in covalency and randomness around Dy3+ with sensitization of Ag and Au NPs. The radiative parameters of 4F9/2?6H13/2 transition of all the glasses disclosed the highest branching ratio (= 85%) indicating lasing potency of the glasses. The stimulated emission cross-sections of Ag sensitized LBSZDy0.9Ag and Au sensitized LBSZDy0.3Au were found to be 79.64×10-22 cm2 and 111.81×10-22 cm2 while the corresponding optical gains were 30.70 ×10-25 cm2 s and 31.35×10-25 cm2 s, respectively. This indicates that Au sensitized LBSZDy0.3Au glass system is better suited for photonics applications compared with Ag sensitized glass systems due to enhanced radiative properties which increased the optical energy harnessing efficiency of the Au NPs embedded glass.
Description
Thesis (PhD (Physics))
Keywords
Physics, Nanoparticles