The physical, structural, elastic, optical and thermal studies on sesquioxides (Al₂O₃, Y₂O₃, Sb₂O₃) doped Oxy Fluoro Cobalt Borate Glasses

Abstract Sesquioxides (Al 2 O 3 , Y 2 O 3 , Sb 2 O 3 ) doped Oxy fluoro Cobalt borate novel luminescent series of glasses are prepared by melt quenching method. The structural characteristics of these glasses were studied by XRD, SEM and EDS techniques. The change in physical parameters such as density of all the series of glasses prepared gives a pathway for cobalt/Alumina/Antimony/Yttrium ions to enter in to borate glass network with the enhancement in the concentration of corresponding dopants. The depolymerization of the borate glass network is evident by the decline in various elastic parameters with B-O-Co/Y/Sb/Al bonds and by the modifier role of CoO/Y 2 O 3 /Sb 2 O 3 /Al 2 O 3 transforming a fraction of tetrahedral BO 3 units into BO 4 units. Both FTIR and IR spectra indicate an increase in octahedral occupancy of cations Co 2+ , Y 3+ , Sb 3+ and Al 3+ ions in the glass network with the increase of their concentration. The conversion rate of tetrahedral BO 3 units to octahedral BO 4 units leading to the formation of NBOs is more in Al 3+ and least in Y 3+ with the increase of concentration of sesquioxides at 0.05 mol% concentration of CoO. The optical absorption spectra of all series of glasses prepared reveal that octahedral occupancy of cobalt ions is dominant due to the ligand fields created by different sesquioxide ions in the glass network produce NBOs and number of electrons trapped at the donor centers. The PL spectra of all the series of these glasses reveal the octahedral occupancy of Co 2+ ions, which is evident from the two emission transitions 2 T 1g (H) → 4 T 1g (F) (531–556 nm) and 2 E g → 5 T 2g (699–718 nm).The prepared series of glasses show efficient luminescence of Cobalt ions, and Al 2 O 3 series of glasses are better candidates for luminescence as their emission Cross-sections are highest when compared with the remaining series of glasses.