Spectroscopic Studies On Sm3+:Tb3+ Codoped Aluminium Borotellurite Glasses For White Light Applications

A new series of Sm3+:Tb3+ codoped aluminium borotellurite glasses have been prepared by melt quenching technique with chemical composition (55-x)B2O3+25TeO(2)+20Al(2)O(3)+0.5Tb(2)O(3)+xSm(2)O(3) (where x= 0, 0.25, 0.5, 1 and 2 wt %). Asymmetric intensity ratio is used to predict the asymmetrical crystal field environment around the Sm3+ ions and asymmetric nature around the Sm3+ ion is found to decrease while increasing the Sm3+ ions concentraion. The decreasing intensity of the Tb3+ ions while increasing the Sm3+ ions concentraion indicates that the interaction between Tb3+ ion and Sm3+ ions. Luminescence intensity decay profile of D-5(4) state of the Tb3+ ions exhibit single exponential for Tb3+ single doped glass and the incorporation of Sm3+ ions convert it into a non exponential nature alongwith decrease in experimental lifetime value of the Tb3+ ions which confirms the energy transfer from Tb3+ ion to Sm3+ ions. The nature of interaction is analysed using IH model and the decay profile fitted with S=6 indicates the dipole-dipole type of interaction between Tb3+ ion and Sm3+ ions. Among the prepared glasses, BTAT0.5S glass possess a better colour coordinates (0.41, 0.43) and colour correlated temperature (CCT) value (3881 K) and the same is suggested for eye safe warm white light applications.