Effects of HfO2 dopant on characteristics of Li2MgTiO4-based red phosphors: Thermal stability, photoluminescence intensity and quantum efficiency improvement

Abstract To produce natural and vivid color, the color rendering index of white light-emitting diodes (WLEDs) with single phosphors is usually lower than 70, which is problematic for LED applications. A commonly used method to resolve this issue is to enhance the red component of WLEDs. In the present study, Hf 4+ and Mn 4+ co-doped Li 2 MgTiO 4 red phosphors are synthesized using a solid-state reaction method. When this red phosphor is excited at 397 and 468 nm, it exhibits weak reabsorption in the blue region and emits a broad and deep red emission band in the range of 640–750 nm, which is attributed to the 2 E g → 4 A 2 g transition. With 5 mol% HfO 2 dopant, the photoluminescence intensity is enhanced by 1.45-fold and thermal stability is increased by 7.7%. Moreover, this red phosphor was applied to a red phosphor-in-glass (RPiG) optical device with a low-melting TeO 2 -B 2 O 3 -ZnO-Na 2 O-WO 3 glass system. In the RPiG melting process, Li 2 MgTiO 4 :Mn 4+ , Hf 4+ red phosphor triggered neither a chemical reaction nor severe degradation, indicating good thermal stability. Li 2 MgTiO 4 :Mn 4+ , Hf 4+ has potential as a red emission material for warm WLED applications.