The effect of MgO doping on the structure and photoluminescence of YAG:Tb phosphor

Abstract

Y 3Al 5O 12 garnet (YAG) phosphor co-doped with Terbium (Tb) and Magnesium (Mg) has been investigated. Tb 3+ ions have a strong trend to transform into Tb 4+ ions under an oxidizing atmosphere. Therefore, this study focused on the effects of structure and optical property of YAG co-doped with Tb 4+ + Mg 2+ in dodecahedral sites. Spherical phosphor particle is considered better than irregular-shaped particle to improve synthesis. Experimentally, solid reactants were mixed with pH-control and spherical particles were obtained using a spray-drying processing. YAG:Tb and YAG:(Tb, Mg) phosphors were synthesized under an attached air by this solid-state reaction method. When MgO is reached to 2.5 at.%, the MgAl 2O 4 phase is formed. The cell parameters are reduced by more MgO amount and a longer soaking time. However, a substitution limit of MgO (2.5 at.%) was observed because of the retarding phenomenon at cell parameters. MgO co-doping damaged the grain growth behavior and caused weaker emitting intensities than single-doped YAG:Tb phosphors. Tb 4+ ions were also induced by MgO co-doping and this paper provided an explanation about Tb 4+ in PL emission spectral analysis.