A novel high color purity blue-emitting phosphor: CaBi₂B₂O₇:Tm³⁺

Graphical abstract: - Highlights: • A series of Tm³⁺-doped CaBi₂B₂O₇ blue-emitting phosphors were prepared. • The optimum doping content of Tm³⁺ ions was found. • The critical distance and concentration quenching mechanism was discussed. • The color purity of as prepared sample was analyzed and compared. - Abstract: A series of Tm³⁺-doped CaBi_2−xB₂O₇:xTm³⁺ (0.02 ≤ x ≤ 0.12) blue-emitting phosphors with high color purity were prepared by solid-state reaction method. The crystal structure and luminescence properties of the as-prepared phosphors were studied. This phosphor shows a satisfactory blue performance (peak at 453 nm) due to the ¹D₂ → ³F₄ transition of Tm³⁺ excited by 357 nm light. Investigation of Tm³⁺ content dependent emission spectra indicates that x = 0.04 is the optimum doping content of Tm³⁺ ions in the CaBi₂B₂O₇ host. The critical distance and the concentration quenching mechanism were also investigated. In particular, the color purity of as prepared sample was analyzed and the result shows that the color purity of CaBi₂B₂O₇:Tm³⁺ is higher than the commercial blue phosphor BaMgAl₁₀O₁₇:Eu²⁺ (BAM:Eu²⁺) and the latest reported Tm³⁺ doped blue phosphors. The present work suggests that the CaBi₂B₂O₇:Tm³⁺ phosphor is a potential blue-emitting candidate for the application in the near-UV WLEDs.