Blue/NIR-emitting Phosphor Based on Sr2CeO4: Tm3+, Yb3+ Obtained by Combustion Synthesis

Abstract

In this study, pure Sr₂CeO₄ (SCO) and codoped Sr₂CeO₄:Tm³⁺, Yb³⁺ (SCO:Tm, Yb) of powder phosphors were synthesized by a combustion technique. The concentration of Tm³⁺ was fixed at 0.5 mol %, while the Yb³⁺ doping concentration was varied from 0 to 7.0 mol %. The crystalline structure, morphology and luminescence properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectroscopy, respectively. The XRD analysis shows the crystalline orthorhombic phase for all synthesized samples of SCO and SCO: Tm, Yb. The SEM results show that the doped sample with 5.0 mol % Yb³⁺ has the lowest grain particle size of 1.92 mm. The SCO:Tm, Yb phosphors produce mainly blue and near infrared emission bands centered at 481 nm and 813 nm (under 980 nm, excitation) which corresponds respectively to ¹G₄→³H₆ and ³H₄→³H₆ transitions of Tm³⁺. In addition, the international commission on illumination CIE coordinates were calculated for all samples taking the range of 400 – 700 nm obtaining for the 5.0 mol % Tm³⁺ doped sample the coordinates: (x,y) = (0.0833, 0.1671) which match with pure blue color. Due to the strong blue and near infrared emissions, the SCO:Tm, Yb phosphors could be good candidates for use in biomarkers or lighting applications.