Structure and luminescence properties of multicolor phosphors based on a new phosphate Ba2In4P6O23

Abstract

White light emitting diodes (WLEDs) of a single matrix have been a hot spot in the research of LED luminescent materials in recent years. Some studies have realized the combination of multiple rare earth ions in a single matrix through the energy transfer between different rare earth ions. As a common green/red emission center used in luminescent materials, Tb³⁺/Eu³⁺ is often co-doped into different hosts. The new host has an important research value due to offering a special crystal-field-environment for the activator. Here, we systematically studied the crystal structure, atomic coordination, chemical bonds, physical and chemical properties of a new compound Ba₂In₄P₆O₂₃. Through first principles and diffuse reflection spectroscopy, it is known that Ba₂In₄P₆O₂₃ has a large optical band gap (4.26 eV), which indicates that the compound has a relatively strong optical absorption in the near-ultraviolet band. A series of Ba₂In₄P₆O₂₃:xTb³⁺, Ba₂In₄P₆O₂₃:yEu³⁺, and Ba₂In₄P₆O₂₃:0.06Tb³⁺,zEu³⁺ phosphors were synthesized by high-temperature solid phase reaction. The luminescence color of the phosphor is adjustable by changing the concentration of doped ions, where Ba₂In₄P₆O₂₃:0.06Tb³⁺,0.03Eu³⁺ phosphor emits white light with CIE coordinates of (0.3399, 0.3595). The decay lifetime curve analysis shows that energy transfer occurs from Tb³⁺ to Eu³⁺ through a quadrupole–quadrupole interaction. The Tb³⁺/Eu³⁺ co-doped phosphor shows higher thermal activation energy and better thermal stability than single-doped phosphors. This research provides a new phosphate matrix material for solid-state illumination, which is expected to promote the development of the lighting field.