Strong f–f excitation in hafnium germanate: Near-UV LED and cathode beam–pumped red phosphor with thermal robustness

Developing narrowband red phosphors has always been a frontier topic in the phosphor community. In this study, a novel hafnium germanate red phosphor, BaHfGe 3 O 9 :Eu 3+ , was successfully synthesized by solid-state reaction method. The phase and crystal structure of BaHfGe 3 O 9 were investigated by the Rietveld refinement of powder X-ray powder diffraction. The band structure was analyzed by density functional theory calculations. Most importantly, the luminescence behavior of phosphors under near-ultraviolet (n-UV) light and cathode rays sources was studied in detail to explore the possibility of their applications in white light-emitting diodes and field emission display. The BaHfGe 3 O 9 :Eu 3+ phosphor exhibits strong f–f excitation and excellent thermal robustness due to Eu 3+ localization in the rigid lattice and asymmetric Ba 2+ sites. Under cathode rays and n-UV light excitation, BaHfGe 3 O 9 :Eu 3+ exhibits narrowband red light emission peaked at 610 nm. Moreover, BaHfGe 3 O 9 :Eu 3+ shows excellent saturation resistance and aging resistance. The performance of the LED lamp encapsulated by the BaHfGe 3 O 9 :Eu 3+ phosphor was studied. The results show that BaHfGe 3 O 9 :Eu 3+ is a potential red phosphor for multifunctional applications.