Site occupancy and luminescence properties of Ca3Ln(AlO)3(BO3)4:Ce3+,Tb3+,Mn2+ (Ln = Y, Gd)

Abstract

In this work, novel single-phase white emitting Ca₃Ln(AlO)₃(BO₃)₄:Ce³⁺,Tb³⁺,Mn²⁺ (Ln = Y and 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 [001] direction, 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 coordination site, while small Mn²⁺ occupied the larger coordination site, which was explained 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 Mn²⁺ generated white emission.