Study of Charge Transfer Green Luminescence in Tb³⁺ Activated BaSrLa₄O₈ Nanophosphor for Advanced Indoor Lighting Applications

A Tb³⁺-activated orthorhombic BaSrLa₄O₈ nanocrystal system with good green luminescence was prepared using the energy-saving combustion method. Its crystal structure is orthorhombic, it belongs to the Pnma (162) space group, and its particle shape and diameter range from 42 nm to 66 nm. Morphological aspects were examined by scanning and transmission electron microscopies. When exposed to ultra-violet radiation, the nanocrystal emits vibrant green light with a wavenumber of 18 348 cm^–1 due to the change of electronic state ⁵D₀ → ⁷F₂. The effect of energy transfer is also demonstrated. The maximum emission intensity was observed at 5.0 mol % Tb³⁺ concentration when excited at 281 nm. This phenomenon can be attributed to the concentration-quenched d–d interaction leading to decreased luminescence intensity. According to the chromaticity diagram, the composite color falls in the green region and the relative color temperature of the optimized sample BaSrLa_3.8Tb_0.2O₈ is measured at 5688 K. These nanocrystals are especially best for producing white light for advanced optoelectronic applications.