Tri-doped Ln3+ ions in barium zinc borate glasses: Luminescence behavior at room and cryogenic temperatures

Abstract

The research work carried out in the paper reports on the effect of BaO and tri doped Er3+, Tb3+, and Gd3+ ions on luminescence characteristics in zinc borate glasses. The work emphasizes the effect of BaO on tri-doped lanthanide ions in borate glasses. The addition of 5 mol% BaO content in the glasses shows more non-bridging oxygens and decreases with addition of BaO content (10 mol%). Glasses show emissions at 311 nm, 543 nm, and 1540 nm for Gd3+, Tb3+, and Er3+ ions, respectively. The Judd-Ofelt method was applied to bring out the significance of the oscillator strength of Tb3+ ions. Higher value of Ω2 was observed in the present glasses indicating their rare-earth covalency is more around Tb3+ ions. Low-temperature luminescence studies were studied for the T2 glass sample for Tb3+ ions. Cryogenic temperature luminescence studies were studied to bring out the significance of 5D4 to 7FJ (J = 3, 2, 1, 0) which is not normally visible at room temperature. The energy is transferred from the Gd3+ to the Tb3+ ions by the Gd3+ ions acting as sensitizers, which helps to adjust the excitation wavelength. Yellowish-green-emitting glasses were observed by illuminating UV light and verified as such from the CIE diagram. The prepared glasses are potential candidate for visible-emitting around yellowish-green colour emitting capability and NIR emitting optical devices and broadband amplifier applications.