Optical properties and energy transfer probing for white light emission in Ce3+/Tb3+/Sm3+ tri-doped barium gallium borosilicate glasses

Switching of three trivalent ions in a host glass may tailor the emission properties. In this direction, singly Ce3+, Tb3+, Sm3+ doped and Ce3+/Tb3+/Sm3+ tri-doped barium gallium borosilicate (CTS) glasses were synthesized and spectroscopic studies viz., optical absorption and photoluminescence were performed to investigate the emission properties. The amorphous nature, thermal stability and functional groups in the glass are identified by x-ray diffraction, differential thermal analysis (DTA), FTIR spectra, respectively. The optical absorption (OA) spectra of triply doped glasses have shown Ce(3+)ion transition 4f (F-2(J)) -> 5d ((2)A(1g)) at 416 nm, four bands from F-7(6) ground state of Tb3+ ions and nine bands from H-6(5/2) ground state in the visible and NIR regions of Sm3+ ions. The evaluated values of optical band gap (E-g) have shown inverse proportionality with Ce3+ ion concentration in Tauc plots and correlated with optical basicity of glasses. The photo luminescence (PL) spectra of Ce3+/Tb3+/Sm3+ tri-doped Ba Ga B Si glass with 0.6 mol % Ce3+ ions (0.6 CTS) have shown maximum emission when excited at 350 nm. The energy transfer (ET) mechanism with dipole-dipole as main interaction between Ce3+ -> (Tb3+ -> Sm3+) ions is evident from all non-exponential time decay curves fitted with I-H (Inokuti-Hirayama) model. The ET efficiency 'eta' is varied from 36.8 to 57.6 %. The colour chromaticity coordinates at 350 nm excitation and emission covered blue (Ce), reddish orange (Sm) and green (Tb) regions. The CCT values of glasses are varying from 1636 K to 6412 K provides the scope for white LED applications.