Enhanced luminescence of CaSb2O6:Bi3+ blue phosphors by efficient charge compensation

This paper reported an enhanced photoluminescence of CaSb₂O₆:Bi³⁺ by efficient charge compensation. Charge compensated CaSb₂O₆:Bi³⁺,M⁺ (M=Li, Na and K) phosphors were prepared using a co-precipitation technique followed by heat-treatment. The structure and morphology of the as-prepared CaSb₂O₆:Bi³⁺,M⁺ samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results revealed that the obtained CaSb₂O₆:Bi³⁺,M⁺ samples are hexagonal crystal structure and this structure was retained regardless of co-doping by Li⁺, Na⁺ or K⁺. All samples showed sphere-like shape with particle size of 40–80 nm. The optical properties of products were studied by UV–vis diffuse reflectivity, photoluminescence spectra and luminescence decay measurements. Under the excitation of 336 nm light, all of the samples exhibited a strong blue emission peaking around 437 nm, which is attributed to the ³P₁–¹S₀ transition of the Bi³⁺ ion. It was found that the charge compensation has significant effect on the photoluminescence properties of CaSb₂O₆:Bi³⁺ and the best luminescence properties have been achieved for CaSb₂O₆:0.75Bi³⁺,0.75 Na⁺. The mechanism for the enhancement of the blue emission has also been studied in detail. Our results suggested that the optical properties of oxide nanostructures can be tailored through co-doping with aliovalent ions and the favorable luminescence properties of CaSb₂O₆:Bi³⁺,Na⁺ make it potential for lighting and display applications.