Energy transfer between terbium and europium ions in barium orthosilicate phosphors obtained from sol-gel route

Abstract The present paper reports on the energy transfer mechanism between Eu 3+ and Tb 3+ in barium orthosilicate obtained from the sol-gel route, when both activators concentration is varied. The synthetic methodology was adjusted to provide high crystalline and monophasic Ba 2 SiO 4 . In the emission spectra under 250 nm excitation, both Eu 3+ ( 5 D 0 → 7 F J ) and Tb 3+ ( 5 D 3 → 7 F J and 5 D 4 → 7 F J ) transitions can be observed at low Eu 3+ doping concentrations with an unexpected and intense blue emission from Tb 3+ . However, when the Eu 3+ content is higher than that of the Tb 3+ , just the Eu 3+ emission is noticed. Also, it is possible to tune the phosphor emission from red to pink by varying the Eu 3+ and Tb 3+ content. From the excitation spectra, we inferred that energy transfer (ET) from Tb 3+ to Eu 3+ occurs at any doping situation, nonetheless, the opposite process happens just when both activators amount is similar. An approach using the Tb 3+ and Eu 3+ lifetimes and the Eu 3+ quantum efficiency confirms this observation, indicating that not only the matrix act as sensitizer to the Eu 3+ ions, but also Tb 3+ ions contribute by increasing the Eu 3+ quantum efficiency in up to 20%. Finally, by using the Van Uitert theory, it was found for this system that the ET between the two rare-earth ions is dominated by the dipole-dipole mechanism.