The optical properties of erbium doped zirconium oxyfluoride tellurite glass embedded with silver nanoparticles

Abstract

Achieving enhanced optical properties of rare earth doped glass by the introduction of metal nanoparticle remains a challenging task. In addition, upconversion emission and infrared emission of erbium doped glass are ever-demanding for a large variety of optical applications. Therefore, in this study four series of erbium doped zirconium oxyfluoride tellurite glasses embedded with silver nanoparticles (Ag NPs) with composition of (90-x)TeO2 – 10MgO – (x)ZrF4 (0 = x = 6 mol%), (84-y) TeO2 - 10MgO - 6ZrF4 - (y)Er2O3 (0 = y = 2 mol%), (88.5-z) TeO2 - 10MgO - (z)ZrF4 - 1.5Er2O3 (0 = z = 4 mol%) and (82.5-w) TeO2 - 10MgO - 6ZrF4 - 1.5Er2O3 - (w)AgCl (0 = w = 1.0 mol%) were prepared using melt quenching technique and investigated through optical characteristics. It is found that, the presence of a broad hump in X-ray diffraction (XRD) pattern confirms the amorphous nature of glass. HTEM images verify the existence of silver nanoparticles with two interplanar spacings about 0.20 nm and 0.23 nm corresponding to d111 and d200 spacing, respectively. The glass density and molar volume are found to be in the range of 4.11-5.09 g/cm3 and 29.1 to 36.9 cm3 mol-1, respectively. It is also found that as the amount of zirconium fluoride is increased, the glass stability increases. The UV-Vis-NIR spectra reveal seven absorption bands centered at 486, 524, 544, 655, 803, 980 and 1526 which are assigned to the transition from ground state 4I15/2 to the various excited levels 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2, and 4I13/2 respectively. Two surface plasmon resonances (SPR) are observed at 530 nm and 570 nm. The optical band gap energy, Urbach energy and refractive index have also been determined, and they were in the range of 2.23 – 3.05 eV, 0.09 – 0.50 eV and 2.384 - 2.650, respectively. The Judd-Ofelt intensity parameter, spontaneous emission probabilities, radiative lifetime and branching ratios of all transitions were calculated based on Judd-Ofelt theory. The upconversion (?e = 980 nm) emission and infrared ( ?e = 633 nm) emission peaks of Er3+ ion exhibit at 525 nm (strong green), 555 nm (moderate green), 657 nm (strong red) and 1530 nm (near-infrared), respectively. The zirconium oxyfluoride tellurite glass sample contains 1.5 mol% Er2O3 and 1.0 mol% of AgCl shows the highest enhancement in the emission peak of 1530nm (4I13/2 ? 4I15/2). The enhancement is attributed to the energy transfer from Ag nanoparticle to Er3+ ions. The result of the present work revealed that the investigated glass can be a potential material for photonic devices and solid state lasers.