La₆Ba₄Si₆O₂₄F₂:Sm³⁺ novel red-emitting phosphors: Synthesis, photoluminescence and theoretical calculations

A series of novel red-emitting La₆Ba₄Si₆O₂₄F₂:Sm³⁺ (LBSOF:Sm³⁺) phosphors was synthesized by a conventional solid state reaction. The crystal structure and atomic coordinates of La₆Ba₄Si₆O₂₄F₂:Sm³⁺ were characterized by Rietveld refinement. Luminescent properties of as-synthesized La₆Ba₄Si₆O₂₄F₂:Sm³⁺ phosphors are studied by measuring the photoluminescence/photoluminescence excitation (PL/PLE) spectra, decay life time, and thermal quenching. The results indicate that composition-optimized LBSO:1%Sm exhibits orange-red emission peaks located at 564, 601, 608 and 648 nm attributed to the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 →⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 transitions of the Sm³⁺ ions correspondingly. In addition, the electronic band structure and density of states for LBSOF and La₆Ba₄Si₆O₂₄F₂:Sm³⁺ are studied by the first principles calculations. The white LED was fabricated by combining a 405 nm chip and blue/green emitting phosphors; the potential of such LED for further applications was demonstrated.