Defect Engineering in a Eu²⁺-Doped β-Al₂O₃ Structure Blue Phosphor and Its Controllable Zero-Thermal Quenching Luminescence

A series of K 1–2 x –2 y Ba y Al 11 O 17 (KBAO): x Eu 2+ phosphors are designed to develop a blue phosphor with excellent thermal properties. All of the samples present similar β-Al 2 O 3 structures with P 63/ mmc space group; the K + vacancy can exist stably until the Ba 2+ concentration exceeds around y = 0.3. KBAO:Eu 2+ exhibits strong absorption for near-ultraviolet light and relatively standard blue emission. The mechanisms for excitation and emission spectrum variations have also been studied in detail. Based on the adjustment of K + vacancy numbers in the defect structure, K 0.6 Ba 0.1 Eu 0.1 Al 11 O 17 exhibits a remarkable quantum yield of around 91.2% and a terrific high-temperature characteristic. The zero-thermal quenching performance mainly results from stabilization of the flowing electron number between Eu 2+ 5d levels and K + defect ε(0/–1) and ε(+1/0) levels in the processes of thermal ionization and recombination. A bright fabricated white-light-emitting diode (WLED) gives a color rendering index (CRI) of R a = 87 and a correlated color temperature (CCT) of 4510 K, demonstrating that KBAO:Eu 2+ has application potential to provide a blue light component in WLED. In addition, our research is a significant attempt to achieving stable zero-thermal quenching by subjective structure design, which provides a reference value for investigating the excellent new phosphors.