A broad-band orange-yellow-emitting Lu2Mg2Al2Si2O12: Ce3+ phosphor for application in warm white light-emitting diodes

Abstract

A new garnet-type Lu₂Mg₂Al₂Si₂O₁₂ compound was successfully synthesized via high-temperature solid–state reaction. The crystal structure was confirmed by the Rietveld refinement method and belongs to a cubic system with a space group of Iad (230) and cell parameters of a = b = c = 11.88310(1) Å. There are two different crystallographic positions for Mg²⁺ with coordination numbers of eight and six, respectively. A relatively large band gap (4.83 eV) was estimated by the diffuse reflectance spectrum, indicating that Lu₂Mg₂Al₂Si₂O₁₂ may be a promising host matrix for luminescent materials. The synthetic Ce³⁺-doped Lu₂Mg₂Al₂Si₂O₁₂ phosphor shows intense and broad-band orange-yellow emission peaking at about 575 nm under near-ultraviolet (n-UV) and blue light excitation. Additionally, the quantum efficiency, thermal stability, and packing performance were investigated to evaluate the practical use in white LEDs. The results indicate that Lu₂Mg₂Al₂Si₂O₁₂: Ce³⁺ may be a promising orange-yellow phosphor for warm white LEDs.