Study on Optical Absorption and Structural Bonding of Lithium Zinc Phosphate Glasses

Abstract

Glasses with chemical composition of (60-x)P2O5-25ZnO-(15+x)Li2O with 0.0 ≤ x ≤ 5.0 mol % are prepared by melt quenching technique. The physical properties, by mean of density and molar volume are determined. The amorphous nature, absorption and structural behaviour are characterized using X-ray Diffraction (XRD), Ultraviolet-visible-near infrared (UV-Vis-NIR) and Fourier transform infrared (FTIR) respectively. In this work, the glass densities are found increases in the range of 2.70 - 2.78 gcm-3 and molar volume decreases from 37.48 - 40.75 gcm-3 with respect to Li2O concentration. Meanwhile, the optical band gap energy for direct and indirect transition are found decreases from 3.074 eV to 2.525 eV and 2.699 eV to 1.670 eV respectively. The Urbach energy is varies as Li2O content increases. The refractive index of these glasses is ranging from 2.48 to 2.90. FTIR spectra exhibited seven bands which centered at 512 cm−1, 767 cm−1, 918 cm−1, 1087 cm−1, 1281 cm−1, 1627 cm−1 and 3441 cm−1 wavenumber that assigned as vibration of Zn-O, symmetric stretching vibration of P-O-P rings, asymmetric stretching vibration of P-O-P groups, asymmetric stretching of PO2-group, asymmetric stretching vibration P=O, bending vibration of water molecule and fundamental stretching of hydroxyl group.