Synthesis, luminescent properties and theoretical calculations of novel orange-red-emitting Ca2Y8(SiO4)(6)O-2:Sm3+ phosphors for white light emitting diodes

The novel orange-red-emitting Ca₂Y₈(SiO₄)₆O₂:Sm³⁺ phosphors (CYSO:Sm³⁺) were synthesized via conventional a solid state reaction. The crystal structure and atomic coordinates of CYSO:Sm³⁺ was characterized by Rietveld refinement. Luminesce properties of as-synthesized CYSO:Sm³⁺ phosphors are carried out by PL/PLE, decay life time, thermal quenching as well as reflectance spectrometer and LED fabrications. The results indicates that composition-optimized CYSO:1%Sm³⁺ exhibits orange-red emission peaks located on 564, 601, 608 and 648 nm attributed to the transitions of 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, respectively. The decay lifetime of CYSO:Sm³⁺ phosphors was in the range of 0.37–1.10 ms. The temperature-dependent photoluminescence is decreased to 80% from room temperature to 150 °C, which is superior to that of commercial red phsophpr-Y₂O₃:Eu³⁺. The results of LED fabrication by combing 405 chips and blue/green phosphors are demonstrated in this study. Finally, from viewpoint of theoretical calculations, band structure and density of state for CYSO and CYSO:Sm³⁺ are studied by first principles calculations. All the results indicate that CYSO:Sm³⁺ phosphors could be a potential material for white light-emitting diodes.