Li+ induced site occupation engineering in Bi3+ activated spinel-type phosphor for multiple optoelectronic applications

Abstract

The utilization of phosphors for information storage, data encryption, temperature sensing, etc. has been becoming a research hotspot. However, modulating dynamic and pluralistic phosphor emissions is still a huge challenge. Herein, we developed a Li⁺-induced site occupation engineering in Bi³⁺ activated Mg₂SnO₄ (MSO) phosphor with multiple emissions and dynamic afterglow for versatile applications. Experiments and first-principles calculations demonstrated that Bi³⁺ would simultaneously enter [MgO₄] tetrahedron and [SnO₆] octahedron to present red and blue emissions, respectively. As Li⁺ ions were introduced into Mg₂SnO₄:Bi³⁺, the preferably generated [LiO₄] could hinder the Bi³⁺ from entering [MgO₄] units, so as to force Bi³⁺ to substitute Sn⁴⁺ in [SnO₆], thereby leading to strengthened blue emission. Due to the distinct luminescence decay of Bi³⁺ in tetrahedron and octahedron units, the luminescence colors were regulated from blue to purple and red with enhancing temperature upon UV light excitation, being suitable for luminescence intensity ratio (LIR) thermometer. Moreover, by virtue of the afterglow properties originating from the inherent oxygen vacancies of Mg₂SnO₄, the dynamic information encryption and anti-counterfeiting by Mg₂SnO₄:Bi³⁺, Li⁺ were achieved. The proposed site occupation engineering can certainly spur several innovative ideas in manufacturing high-performance phosphors for versatile applications.