Luminescence Behavior of the Ba₂HfF₈:Dy³⁺/Sm³⁺ Nanophosphor for White Light-Emitting Applications

Lanthanide (Ln)-doped inorganic materials are widely used in X-ray scintillation, enabling luminescence in the UV to near-infrared region with average lifetime ranging from nanosecond to hours. Fluoride-based inorganic scintillators are favorable due to the low self-absorption. With this motivation, for the first time, this research examines photoluminescence and cathodoluminescence (CL) properties of Dy3+- and Sm3+-doped Ba2HfF8 (BHF). Singly doped BHF emitted characteristic emission from the doped Ln3+ ions under UV excitation. The Dy3+ emission shows only two emission bands, i.e., blue and yellow, ideal for white light emission. Our results clarify the nature of energy transfer between Dy3+ and Sm3+ ions in the binary-doped BHF:DySm. No sensitized-type energy transfer was present among the two dopants. However, nonradiative cross-relaxation energy transfer was present between Dy3+ and Sm3+ ions, causing the deleterious effect on the overall emission intensity of the Dy3+ activator ion. The cathode ray-induced CL indicated that all of the samples were extremely sensitive under high-energy irradiation, emitting visible photons. The present material is a promising white-emitting phosphor for white light-emitting diodes and an X-ray scintillator for visible emission.