Photoluminescence properties of novel Sm3+ and Dy3+ co-activated CsGd(WO4)2 phosphors

• Sm3+ and Dy3+ co-activated CsGd(WO4)2 phosphors were synthesized by sol–gel method.
• Sm3+ and Dy3+ co-activated CsGd(WO4)2 phosphors were characterized by XRD, Raman, PL, SEM.
• The photoluminescence process in the Sm3+ and Dy3+ co-activated CsGd(WO4)2 phosphors was described.
• The emission lies in the greenish-yellow and warm white.
• CIE color coordinates and CCT values were estimated.

CsGd(WO4)2 (CGW) phosphors with different concentration of singly-doped Sm3+ or Dy3+ ions and co-doped Sm3+/Dy3+ ions were prepared through polymeric sol–gel method. The phosphors were characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman and luminescence analysis. The excitation spectra of the phosphors reveal a broad charge transfer band in the short wavelength region and several sharp lines in the longer wavelength region which indicates that these phosphors can be effectively excited by UV and blue LED’s. The CGW: Dy3+, Sm3+ phosphors exhibit the emission peaks in the blue (4F9/2 → 6H15/2), yellow (4F9/2 → 6H13/2) and orange–red (4G5/2 → 6HJ=5/2, 7/2, 9/2) regions under the excitation wavelength of 365 nm. The emission spectrum of the co-doped phosphors explains the spread of sensitizing effects from the Dy3+ ions to the Sm3+ ions. All the decay curves are well fitted by the bi-exponential functions. White color chromaticity coordinates (x = 0.33, y = 0.33) were achieved by optimizing the doping concentration of Sm3+ in Dy3+ doped CGW phosphors.

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