Enhancement of green emission from Ca14Al10Zn6O35: Tb3+ phosphors via cross-relaxation energy transfer by Li+ ions

Highlights: • Green and blue emission are observed from Tb³⁺ doped Ca₁₄Al₁₀Zn₆O₃₅ phosphors. • Green emission is enhanced when Li⁺ ions are co-doped to the composition. • CRET efficiency and energy transfer rate are improved with the introduction of Li⁺ ions. • The synthesize green-emitting phosphors exhibit good thermal stability. Tb³⁺ doped Ca₁₄Al₁₀Zn₆O₃₅ phosphors were prepared by a traditional solid-state reaction approach. The Tb³⁺ doped phosphors exhibit blue and green emission under the 285 nm excitation. The green to blue emission ratio is gradually enhanced as the Tb³⁺ concentration increases, which is ascribed to the enhanced cross-relaxation energy transfer (CRET) processes between Tb³⁺ ions. Li⁺ ions were introduced to the composition as an attempt to address the charge mismatch induced by Tb³⁺ for Ca²⁺ ion substitution. An enhancement of green emission from Tb³⁺ ions is observed after co-doping with Li⁺ ions. The lifetime measurement confirms that the CRET efficiency and energy transfer rate are simultaneously increased by Li⁺ ions. The results suggest that the incorporation of Li⁺ ions is a feasible approach to overcome charge vacancy defects and enhance CRET processes.