Structural and Luminescence Properties of Yellow-Emitting NaScSi2O6:Eu2+ Phosphors: Eu2+ Site Preference Analysis and Generation of Red Emission by Codoping Mn2+ for White-Light-Emitting Diode Applications

The structural properties of clinopyroxene NaScSi2O6 have been investigated using the X-ray powder diffraction refinement, and the luminescence properties of Eu2+ and Eu2+/Mn2+-activated NaScSi2O6 have been studied to explore the new materials for phosphor-converted white light ultraviolet light-emitting diodes (UV-LEDs). Eu2+ was introduced into the NaScSi2O6 host in the reducing atmosphere, and the preferred crystallographic positions of the Eu2+ ions were determined based on the different structural models of the NaScSi2O6 host. The as-obtained NaScSi2O6:Eu2+ phosphor shows greenish yellow emission with the broad-band peak at 533 nm, and efficient energy transfer (ET) takes place between Eu2+ and Mn2+ in NaScSi2O6, leading to a series of color-tunable phosphors emitting at 533 and 654 nm for the designed NaScSi2O6:Eu2+,Mn2+ phosphors under excitation at 365 nm. The ET mechanism of Eu2+ and Mn2+ has also been evaluated. We have demonstrated that NaScSi2O6:Eu2+ and NaScSi2O6:Eu2+,Mn2+ materials exhibit great potential to act as the effective phosphors for UV-LEDs.