Site Occupancy and Luminescence Properties of Ca3Ln(AlO)3(BO3)4:Ce3+,Tb3+,Mn2+ (Ln = Y, Gd) Phosphors for White-LEDs
In this work, novel single phase white emitting Ca3Ln(AlO)3(BO3)4:Ce3+,Tb3+,Mn2+ (Ln = Y, Gd) phosphors were synthesized by a conventional solid-state reaction method. The crystal structure and photoluminescence properties were investigated for the first time. The structure of Ca3Ln(AlO)3(BO3)4 was formed by AlO6 octahedral chains interconnected by BO3 triangles. Along the , the Ca/Ln cations fill in the trigonal and hexagonal tunnels. For Ca3Ln(AlO)3(BO3)4:Ce3+ and Ca3Ln(AlO)3(BO3)4:Mn2+, large Ce3+ preferred to occupy the smaller sites while small Mn2+ occupied the larger sites, which was interpreted by the space hindrance. Due to the cation disorder, the local environment of Ce3+ was complicated and the emission band was extremely broad. In Ca3Ln(AlO)3(BO3)4, the emission color can be tuned from blue to green or red by tuning the Ce3+-Tb3+ or Ce3+-Mn2+ concentration based on energy transfer. Thus, the combination of blue, green and red emitting Ce3+, Tb3+ and Mn3+ generated white emission.