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

Abstract

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