Structural, morphological and optical properties of bimetallic nanoparticles in tellurite glass system for improvement in surface- enhanced raman scattering

• Main Author: Ixora Ferodolin
• Format: Thesis
• Language: English; English
• Published: 2020
• Subjects: TP785-869 Clay industries. Ceramics. Glass
• Online Access: https://eprints.ums.edu.my/id/eprint/41103/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/41103/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/41103/

Combining bimetallic nanoparticles (NPs) with rare-earth ions in tellurite glass is an interesting field for researchers due to the amplification in surface-enhanced Raman scattering (SERS). To ensure the SERS effect to occur, a selection of SERS substrate is very crucial as their plasmonic properties and nanostructured metallic surface will stimulate the plasmonic excitation for Raman scattering to take place. Determining the SERS enhancement in tellurite glass with addition of bimetallic NPs is the main focus of this research. Four series of glass are prepared via melt-quenching method. Glass containing monometallic titanium NPs with erbium content are prepared with composition of (70-x-y)TeO2–20ZnO–9Na2O–1Er2O3–(x)TiO2–(y)Al2O3, where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 mol% and y = 0 mol%. Glass containing monometallic titanium NPs without erbium content are prepared with composition of (70-x-y)TeO2– 20ZnO–9Na2O–0Er2O3–(x)TiO2–(y)Al2O3, where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 mol% and y = 0 mol%. In contrary, glass containing bimetallic titanium and aluminium NPs with erbium content are prepared with composition of (70-x-y)TeO2– 20ZnO–9Na2O–1Er2O3–(x)TiO2–(y)Al2O3 where x = 0.0 and 0.3 mol% and y = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mol%. Glass containing bimetallic titanium and aluminium NPs without erbium content are prepared with composition of (70-x-y)TeO2–20ZnO–9Na2O–0Er2O3–(x)TiO2–(y)Al2O3 where x = 0.0 and 0.3 mol% and y = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mol%. In-depth characterization are performed by using X-Ray Diffraction (XRD), Ultraviolet-Visible Spectroscopy (UV-VIS) Fourier-Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Photoluminescence Spectroscopy (PL), Atomic Force Microscopy (AFM) and Raman Spectroscopy. XRD spectra confirms the amorphous nature of glass samples with the appearance of broad hump between 25° to 35° and the absence of sharp peak. A weak plasmon band is observed at 550 nm for glass containing monometallic titanium NPs. Meanwhile, a weak plasmon band is observed at 554 nm and 827 nm for glass containing bimetallic titanium and aluminium NPs. The variations in the direct optical band gap, indirect optical band gap and Urbach energy is due to the contribution of metallic NPs. FTIR spectra shows the appearance of Zn−O tetrahedral bond, symmetric stretching vibrations of Te−O in Te, Te−O−Zn linkages, vibrations of water molecules and fundamental stretching of hydroxyl group for glass containing monometallic NPs. Glass containing bimetallic NPs display the Zn−O tetrahedral bond, stretching vibrations of Al−O, Te−O bending vibrations in TeO3 units, Al−O stretching, vibrations of water molecules and fundamental stretching of hydroxyl group. TEM image display the increasing size of NPs following the Ostwald ripening process and coalescence process. AFM image illustrates the formation of scattered island due to NPs. PL emission spectra display the two significant peaks centred at 547 nm and 668 nm with enhancement in intensity due to the surface plasmon resonance (SPR) effect. Raman spectra illustrate the amplification in Raman signal with Raman enhancement factor of 1.55, 1.45, 1.51 and 1.61 for TZNETiAl0.6 glass. The amplification in Raman signal due to excitations of surface plasmon from titanium and aluminium NPs. TZNETiAl0.6 glass shows optimum properties to be used in molecular detection application due to favourable surface roughness value which is suitable for substrate properties and highest enhancement intensity in PL and Raman spectra attribute to the plasmonic effect from titanium and aluminium NPs.