Effect of Nd2O3 / Y2O3 doping on the physical, elastic, structural and optical properties of lead borotellurite glass system / Siti Nasuha Mohd Rafien

Two series of lead borotellurite glasses doped with neodymium and yttrium oxide with the composition of (49-x)H3BO3-35TeO2-15PbO-1.0Y2O3-xNd2O3 (Nd-series glass) and (49-x)H3BO3-35TeO2-15PbO-1.0Nd2O3-xY2O3 (Y-series glass) where 0.0 ≤ x ≤ 2.5 mol% were prepared using melt-quenched method. The physical properties of all glass such as density, molar volume, oxygen packing density as well as elastic properties were measured. The structural properties of the glasses were studied using X-ray diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy and Energy Dispersive X-ray (EDX) spectroscopy analysis. The amorphous nature of the glass was investigated through XRD analysis, and all glass were confirmed.to be amorphous in nature. FTIR and Raman analysis revealed the presence of Te-O bond in TeO4, TeO3 and B-O bond in BO4 and BO3 in the prepared glasses. FTIR spectra analysis also indicated that the addition of Nd2O3 and Y2O3 content in the glass system tends to change the glass network due to the transformation of TeO4 into TeO3 and BO4 into BO3 and vice versa. Raman analysis showed there are some structural changes as dopant were added into the glass system where BOs and NBOs were created at the same time. The presence of all elements in the glass system were confirmed using EDX analysis. The optical properties of the glasses were tested using UV-Vis NIR and photoluminescence spectroscopy. The UV-Vis NIR results for both series glass shows eleven absorption peaks which are related to the main absorption spectra of Nd3+ ions. The absorption peaks that correspond to the transitions from the 4I9/2 ground state to the (2P1/2 + 2D5/2), 2D3/2, (2G5/2, 2K15/2), 4G9/2, 4G7/2, (4G5/2, 2G7/2), 2H11/2, 4F9/2, (4S3/2, 4F7/2), (4F5/2, 2H9/2) and 4F3/2 excited state. The optical band gap, Eopt shows that the Eopt for Nd-series glass increases and for Y-series glass initially decreased before slightly increasing with respect to the composition changes. The increase of Eopt in both series glass suggests the formation of BOs with respect to composition while the initial decrease of Eopt in Y-series glass was caused by weaker bond strength of yttrium oxide compared to other chemical oxide in the glass matrix. As the bond strength of Y-O bonds replace the other chemical bonds with larger bond strength, the average bond strength of the glass system will be decreased. As a result, the conduction band edge energy and the Eopt will reduce as well. The photoluminescence data reveal that for Nd2O3 concentration higher than 1.0 mol% and for Y2O3 concentration higher than 1.5 mol%, the photoluminescence peaks decreased in intensity. These concentrations represent the quenching concentration.