Reddish-orange-emitting and paramagnetic properties of GdVO4:Sm3+/Eu3+ multifunctional nanomaterials

Abstract

A series of GdVO₄:Sm³⁺,Eu³⁺ reddish-orange-emitting nanophosphors were successfully prepared by a simple one-step hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra, fluorescence lifetime, PL quantum-efficiency (QE) and vibrating sample magnetometer (VSM) were utilized to characterize the as-prepared samples. The results show that the individual Sm³⁺ or Eu³⁺ ion activated GdVO₄ phosphors exhibit excellent emission properties in their respective regions and the bright blue light from VO₄³⁻ group can be observed upon excitation of ultraviolet light (313 nm). The emission intensity of Sm³⁺ singly activated GdVO₄ phosphors reaches the maximum when the content of Sm³⁺ is 0.025, of which the critical distance (R_Sm–Sm) is calculated to be 18.42 Å. Strong reddish-orange emissions can be seen in Sm³⁺ and Eu³⁺ ion co-doped GdVO₄ phosphors under ultraviolet light irradiation. In addition, the energy transfer phenomenon from Sm³⁺ to Eu³⁺ ions is clearly observed in GdVO₄:Sm³⁺,Eu³⁺, which is confirmed to be an electric quadrupole–quadrupole interaction and the energy transfer efficiency can reach a maximum at 92.5%. More significantly, the color becomes more saturated with the increase of the content of Eu³⁺ or Sm³⁺ ions. Moreover, the as-prepared samples exhibit paramagnetic properties at room temperature. This type of multifunctional reddish-orange-emitting nanophosphor has promising applications in the fields of UV/n-UV WLEDs and biomedical science.