Spectroscopic, photometric properties and energy transfer mechanism of white light emitting Li2SiO3:Tb3+, Eu3+, Mn4+ phosphors

Abstract

In this communication, we report a new kind of trichromatic white light emitting Li₂SiO₃ (LMS): xTb³⁺, yEu³⁺, zMn⁴⁺ phosphors which were prepared by solid-state reaction method. Powder X-ray crystallographic structural analysis indicates that the sample has an orthorhombic crystal structure with the Cmc21 space group. The photoluminescence excitation and emission spectra of the LMS: 0.04Tb³⁺, 0.04Eu³⁺, zMn⁴⁺ phosphors were clearly monitored. The emission of three main colours, green, orange-red and rich red, was obtained from Tb³⁺, Eu³⁺, and Mn⁴⁺, respectively. Energy was transferred from Tb³⁺ → Eu³⁺ → Mn⁴⁺ ions, as the interactions of electric quadrupole–quadrupole (q-q) with the efficiencies of 76.6%, which resulted in the enhancement of luminescence intensity. In addition, average life time decay was determined by using double exponential fit, yielding a value of 0.286 ms under 378 nm excitation. It is noteworthy that the LMS: 0.04Tb³⁺, 0.04Eu³⁺, zMn⁴⁺ can produce white light when the Mn⁴⁺ ratio is adjusted appropriately during ultraviolet excitation. Furthermore, for the phosphors as made, the temperature-dependent luminescence spectra show good thermal quenching characteristics. The results suggest that the LMS: 0.04Tb³⁺, 0.04Eu³⁺, zMn⁴⁺ phosphors can be exploited in solid state lighting applications.