Photoluminescence properties, energy transfer and thermal stability of the novel red-emitting CaGd2(WO4)4:Eu3+, Sm3+ phosphors

- The novel red CGW phosphor belongs to the scheelite structure with the monoclinic space group I2/b.
- The Eu3+ ions mainly occupy the lattice site without inversion symmetry in CGW phosphor, which leads to better color purity.
- The energy transfer from Sm3+ to Eu3+ has been confirmed, and the energy transfer efficiency is calculated to be 23.34%.
- The thermal activation energy ΔE of CGW: Eu3+,Sm3+ phosphor is determined to be 0.305 eV.

Red-emitting CaGd2-x-y(WO4)4:xEu3+,ySm3+ phosphors have been synthesized by the solid state reaction method. The crystal structure and luminescent properties have been investigated by X-ray powder diffraction (XRPD) and photoluminescence spectra. The results show that CaGd2(WO4)4 phosphor has monoclinic system with space group I2/b. CaGd2(WO4)4:Eu3+,Sm3+ phosphor can be effectively excited by near-UV, and the emission spectrum exhibits the strongest red emission peak corresponding to the 5D0 → 7F2 transition of Eu3+ ions. The effective energy transfer from Sm3+ to Eu3+ in CaGd2(WO4)4:Eu3+,Sm3+ has been confirmed by photoluminescence and decay measurement, and the energy transfer efficiency is calculated to be 23.34%. Furthermore, the temperature dependent luminescence of the CaGd2(WO4)4:Eu3+,Sm3+ phosphor has been studied, and the thermal activation energy ΔE is found to be 0.305 eV. These results show that CaGd2(WO4)4:Eu3+,Sm3+ phosphor can be a potentially better red emitting phosphor for white light emitting diodes (LEDs).

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