Influence of silver nanoparticles on optical properties of erbuim-samarium co-doped sodium lithium phosphate glass

Abstract

This thesis reported the influence of silver nanoparticles on the optical properties of erbium (Er3+) and samarium (Sm3+) ion co-doped sodium lithium phosphate glass. A series of glass with composition of (59-x)P2O5-(x)Na2O-30Li2O- 0.5Er2O3-0.5Sm2O3 (where x = 10, 15, 20, 25 and 30 (in mol%)), (49.5-y)P2O5- 20Na2O-30Li2O-(y)Er2O3-0.5Sm2O3 (where y = 0.2, 0.4, 0.6, 0.8 and 0.10 (in mol %)) and 48.5P2O5-20Na2O-30Li2O-0.5Sm2O3-1.0Er2O3-(z)AgCl (where z = 0.01, 0.03, 0.05, 0.07 and 1.00 (in gram)) were prepared using melt quenching technique. These samples were characterized using X-ray diffractometer (XRD), Transmission Electron Microscope (TEM), Differential Thermal Analysis (DTA), Fourier Transform Infrared (FTIR) spectrometer, Energy Dispersive X-ray (EDX) spectrometer, UV- Vis NIR spectrophotometer and Photoluminescence (PL) spectrometer. The XRD pattern confirms the amorphous nature of the glass and existence of silver nanoparticles with average diameter estimated to be —0.615 nm was revealed by TEM image. Thermal stability is found to vary in the range of 143 °C to 197 °C. Five major IR absorption peaks were found at 580 cm-1, 763 cm-1, 920 cm-1, 1055 cm-1 and 1128 cm-1 which attributed to P-O-P bending vibrations, P-O-P symmetric stretching vibrations, P-O-P asymmetric stretching vibrations, (P-O)- asymmetric stretching vibrations and P=O asymmetric stretching vibrations respectively. The EDX data showed all the elements in the composition were present. The UV absorption spectra showed 12 peaks that belongs to both Er3+ and Sm3+ ions. The indirect optical energy band gap and Urbach energy were in the range of (3.43 - 3.52) eV and (0.23 - 0.40) eV respectively. Four prominent peaks are evidenced, which are assigned to various transitions among Sm3+ excited states to the ground state such as 4G5/2 ^ 6H5/2 (560 nm), 4G5/2 ^ 6H7/2 (596 nm), 4G5/2 ^ 6H9/2 (640 nm) and 4G5/2 ^ 6Hi 1/2 (704 nm). Judd Ofelt analysis sho^vs the trends in parameter which is Q2 > Q4 > Q6 and spectroscopic quality factor, Q has the highest value with 4.14 for z(0.05) and the lowest for z(0.07) which is 3.48. The average electric dipole (Aed), radiative lifetimes ( z rad) and branching ratios ( f3 ) are estimated for Sm3+ ions glass matrices. It is observed that the 6F3/2 transition have higher branching ratio values (99.93%) in all five samples. Among these five transitions, 6HJ5/2 transitions in z(0.01) have the lowest values (42.17%). The photoluminescence intensity of Sm3+ is found to greatly enhance with the increase of Er3+ ion concentration together with Ag NPs in the glass matrix. Radiative properties such as stimulated emission cross section ( j ), peak wavelength ( Xp), effective emission bandwidth (A A f) and gain bandwidth (A G) were measured. The values of j for 4G5/2 emission transition are in the order of 4G5/2 ^ 6H5/2 > 6H7/2 > 6H9/2 > 6H: 1/2 for all samples. z(0.10) has the maximum value of A G for all transition parameters and the highest one is at 4G5/2 ^ 6Hi y2 transition (12.72 x 10-27 cm3). Based on the result, it can be concluded that these glasses have a potential for the development of solid state laser application and photonic devices.