Improvement of thermal stability and photoluminescence in Mg2Y2Al2Si2O12:Ce3+ by the cation substitution of Ca2+, Sr2+ and Ba2+ ions

Abstract

The luminescence of Ce³⁺ in Mg₂Y₂Al₂Si₂O₁₂ (MgYAlSiO₆) can be controlled by substituting with Ca²⁺, Sr²⁺, and Ba²⁺ ions. The materials show blue shifts in their emission spectra that become highly evident with the increase in the ionic radius, and this phenomenon is the result of the combined action of the nephelauxetic effect and crystal field splitting. Due to the introduction of Ca²⁺, Sr²⁺, and Ba²⁺, the distortion of the crystal decreases and the structural rigidity and stability increase, improving the quantum efficiency and temperature stability of Mg₂Y_1.93Al₂Si₂O₁₂:0.07Ce³⁺. Mg₂Y_1.93Al₂Si₂O₁₂:0.07Ce³⁺,Ca²⁺ is more stable than Mg₂Y_1.93Al₂Si₂O₁₂:0.07Ce³⁺,Sr²⁺/Ba²⁺ because the radius of Sr²⁺/Ba²⁺ is larger than that of Mg²⁺. The Mg_1.9Y_1.93Al₂Si₂O₁₂:0.07Ce³⁺,0.1Ca²⁺ fluorescent powder and blue chip were packaged to obtain warm white light-emitting diodes (LEDs) with luminous efficiency of 60 lm W⁻¹. These results show that the Mg₂Y₂Al₂Si₂O₁₂:Ce³⁺ phosphor has potential application value in white LEDs.