Synthesis, structure and optical properties of novel thermally robust Dy3+-doped Ca9Sc(PO4)7 phosphors for NUV-excited white LEDs

Abstract The powder samples of Ca9Sc(PO4)7:xDy3+ white emitting phosphors are prepared via a solid state reaction technique. The Ca9Sc(PO4)7:Dy3+ samples are researched by using the GSAS Rietveld refinement and X-ray diffraction (XRD) methods, and SEM images and elemental maps are recorded. Under 350 nm excitation, the emission spectra of Ca9Sc(PO4)7:xDy3+ samples have two obvious peaks and one weak peak at 484, 572 and 660 nm, corresponding to the characteristic electron transitions of (4F9/2→6H15/2, blue), (4F9/2→6H13/2, yellow) and (4F9/2→6H11/2, red), respectively. The concentration quenching effect, decay lifetime and thermal quenching of the as-synthesized Ca9Sc(PO4)7:Dy3+ samples are researched systematically The Ca9Sc(PO4)7:0.02Dy3+ phosphor possesses a good thermal stability, of which the emission intensity at 423 K could maintain 79% of the initial value (273 K). In addition, through the study of the chromaticity coordinates of the Ca9Sc(PO4)7:0.02Dy3+ phosphor, it is found that it is located in the white region, and the Commission Internationalede L’Eclairage (CIE) chromaticity coordinates are (0.339, 0.389). The above results show that Ca9Sc(PO4)7:xDy3+ phosphors can be an excellent candidate material for applications in NUV-excited white LEDs.