Study on mechanism controlling ⁵D₃/⁵D₄emissions of Tb³⁺ in glasses

Tb³⁺ doped SiO₂-ZnO-BaO glasses are prepared by melting quenching method and their unique photoluminescent properties for the UV excitation are studied by using emission/excitation spectra and decay curves. Glasses in the composition (mol%) of 60SiO₂-xZnO-(40-x)BaO-0.2Tb³⁺(x=30, 20, 10) show the strongest emission peaking at 436 nm which is different from majority of other reported work. Lower content of the free OH groups mainly contribute to this phenomenon due to the decreased probability of the multi-phonon aided non-radiative relaxation process from ⁵D₃ to ⁵D₄ energy levels of Tb³⁺ ions. The Tb³⁺ concentration also affects the ⁵D₃/⁵D₄ emissions as a result of the cross-relaxation effect on two nearby Tb³⁺ ions (⁵D₃-⁵D₄⇒⁷F₆-⁷F₀). Moreover, by adjusting Tb³⁺ concentration and/or ZnO/BaO concentration ratio of the host glass we obtained the adjustable emission with the required CIE chromaticity from blue to green, suggesting that the present Tb³⁺-doped SiO₂-ZnO-BaO glasses are potential as blue/green dual-color luminescent materials for different applications.