Optical Properties of Tellurite Based Glasses Doped with Dy  for Photonic Applications

Ejigu, Afrash

dc.contributor.author	Ejigu, Afrash
dc.date.accessioned	2024-03-28T06:41:08Z
dc.date.available	2024-03-28T06:41:08Z
dc.date.issued	2023-06
dc.identifier.uri	http://ir.bdu.edu.et/handle/123456789/15749
dc.description.abstract	n this thesis work, Zinc Niobo Tellurite (TNZ) and Cadmimun Niobo Tellurite (TNC) glass systems with general formula (70-y-z)TeO 2 -(20-x)Nb 2 O 5 -(10+x) ZnO-yEu -z Dy 2 O 3 and (70-y-z)TeO 2 -(20-x)Nb 2 O 5 -(10+x) CdO-yEu 2 O 3 -z Dy 2 O with x = 0,5,10; y,z = 0,1 ( y=z1 ) mol% respectively are investigated. 3 The glasses have been prepared using the melt quenching method. Densities of the obtained glasses were measured and the packing density was calculated. Raman spectra of the present glass samples were measured in the range of 200–1,000 cm -1 . For the TNZ glass system, increase in the modifier zinc oxide (ZnO) content from 10 mol% to 20 mo% in un-doped glasses showed a significant shift of band positions attributed to vibrations of trigonal bipyramid [TO 4 ] structural units from 637-667cm -1 and bending vibrations of trigonal pyramid [TeO 3 ] units from 506-541cm -1 . This increase in frequency is attributed to the decrease in bond lengths of Te-O in TeO 4 and TeO structural units. But in the case of rare earth-doped TNZ glasses the band positions of the above structural units are observed to shift slightly towards shorter wavenumbers. The peak shift, full width at half maximum of de-convoluted Raman spectra of TeO 3 4 and TeO structural units in these glasses were analyzed to investigate the local environment. It is observed that these tellurite glasses are good host for rare earth ions as they offer voids in the network. The doped rare earth ions are not seen to change the local environment too much but Dy ion has a slightly more tendency to polarize Tellurium-Oxygen (Te-O) bonds than the Eu ions. 3 The optical properties of these glasses have been investigated using absorption spectra. The bonding parameters (δ and β), optical band gap, Urbach‘s energy, and Judd-Ofelt (JO) intensity parameters were calculated from the absorption spectra. The JO intensity parameters have been used to explore the nature of the bonding and asymmetry around the Dy-ligand field environment. The JO parameters are in turn used to determine the radiative parameters such as radiative transition probabilities, branching ratios and radiative lifetimes have been estimated for the excited levels of Dy 3+ ions. The results obtained have been compared with that of Dy 3+ -doped tellurite based glasses from literature. 2 O 3 vii Laser induced photoluminescence of Eu 3+ -doped tellurite-based glasses was investigated. Europium oxide is found to be efficient in fluorescing in the visible as well as in the IR wavelength with laser excitation	en_US
dc.language.iso	en_US	en_US
dc.subject	Physics	en_US
dc.title	Optical Properties of Tellurite Based Glasses Doped with Dy for Photonic Applications	en_US
dc.type	Dissartation	en_US