Pressure-controlled synthesis of high-performance SrLiAl3N4:Eu2+ narrow-band red phosphors

Abstract

SrLiAl₃N₄:Eu²⁺ (SLA) phosphors have gained increasing attention worldwide due to their narrow emission bandwidth and excellent thermal stability. In this study, a series of SLA phosphors are synthesized at gas pressures ranging from 0.1 MPa to 100 MPa using gas pressure sintering and hot isostatic press systems. Upon elevating the gas pressure in synthesis, the volume of a unit cell slightly decreases while both the quantum efficiency and the particle size of SLA increase. The Eu²⁺/Eu³⁺ ratio also increases with applied pressure, thereby enhancing the luminescence intensity of the phosphor materials. The presence of Li defects in the host material is evidenced by inductively coupled plasma with atomic emission spectroscopy. The mechanism of controlling the oxidation state of Eu and defect formation is proposed to elucidate the behavior of phosphors under different applied pressure levels during synthesis. Finally, the LED package shows that SLA could be a potential candidate for backlighting.