Synthesis, luminescence properties and theoretical calculations of La₅BSi₂O₁₃:Dy³⁺ phosphor coatings for light-emitting diodes

In this study, we propose a white-emitting phosphors-La₅BSi₂O₁₃:Dy³⁺ synthesized by a conventional solid state reaction. The phase purity, crystal structure, luminescence properties as well as thermal stability and chromaticity coordinates were investigated in this study. The excitation spectra of as-synthesized phosphors were characterized by sharp band extending from 300 to 500 nm. Under 348 nm excitation, La₅BSi₂O₁₃:Dy³⁺ exhibits three emission peaks at 477 nm (blue region), 570 nm (yellow region) and 663 nm (red region) which correspond to ⁴F_9/2→⁶H_15/2, ⁴F_9/2→⁶H_13/2 and ⁴F_9/2→⁶H_11/2 transitions of Dy³⁺, respectively. The emission intensity was only decreased 13% from room temperature to 150 °C, which indicated that La₅BSi₂O₁₃:Dy³⁺ phosphor possessed excellent thermal stability. Furthermore, The CIE chromaticity color coordinates of La₅BSi₂O₁₃:Dy³⁺ phosphor falls in the yellowish white region. In addition, theoretical calculations of La₅BSi₂O₁₃ and La₅BSi₂O₁₃:Dy³⁺ are also carried out by first principle calculations for comparison. The results indicate that La₅BSi₂O₁₃:Dy³⁺ is a potential candidate for white light-emitting diode applications.