Synthesis and photoluminescence of novel blue-emitting phosphor of Eu2+-activated fluoroborate BaGaBO3F2

Pure and Eu²⁺-activated fluoroborate BaGaBO₃F₂ was prepared using high-temperature solid-state reaction. BaGaBO₃F₂ is a wide band semiconductor with the indirect transition characteristic. The excitation and luminescence spectra of the phosphor were measured, and it was found that Eu²⁺-activated BaGaBO₃F₂ exhibits a bright blue color under ultraviolet (UV) light. The narrow emission band peaked at 425 nm is attributed to the transitions of 4f⁶5d→4f⁷(⁸S_7/2), and the Stokes shift estimated for this phosphor sample is 3140 cm⁻¹. The lifetime of the luminescence is also reported. The absolute quantum efficiency (QE) of the phosphor was evaluated, and it was found that the absolute QE decreases with increasing Eu²⁺ concentration. The phosphor shows an excellent quantum efficiency of 72.5% and a high thermal activation energy of 0.342 eV. The study concludes that Eu²⁺-doped BaGaBO₃F₂ phosphor has promising luminescence application abilities and can be used as a blue-emitting phosphor in a variety of applications.