Facile one-step hydrothermal synthesis and luminescence properties of Eu³⁺-doped NaGd(WO₄)₂ nanophosphors

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Eu<SUP>3+</SUP>-doped NaGd(WO<SUB>4</SUB>)<SUB>2</SUB> nanophosphors were synthesized via a facile one-step hydrothermal method without any surfactants or a further heat treatment. X-ray powder diffraction (XRD), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), the photoluminescence (PL) excitation and emission spectra, and decay curves were used to characterize NaGd(WO<SUB>4</SUB>)<SUB>2</SUB>:Eu<SUP>3+</SUP> phosphors. The results show that the Eu<SUP>3+</SUP>-concentration has little influence on the structure and morphology of the as-synthesized samples. However, pH value plays a vital role on the structure and morphology of NaGd(WO<SUB>4</SUB>)<SUB>2</SUB>. The well-crystallized sheet-like NaGd(WO<SUB>4</SUB>)<SUB>2</SUB> phosphors can be obtained only at pH = 5–7. On the basis of the time-dependent synthesis, a possible growth mechanism of sheet-like architectures is proposed. The luminescence properties of NaGd<SUB>1-x</SUB>Eu<SUB>x</SUB>(WO<SUB>4</SUB>)<SUB>2</SUB> (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu<SUP>3+</SUP> shifts to lower energy and broadens with increasing the Eu<SUP>3+</SUP>-concentration.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NaGd(WO<SUB>4</SUB>)<SUB>2</SUB>:Eu<SUP>3+</SUP> nanosheets were synthesized by facile one-step hydrothermal method. </LI> <LI> Luminescence properties of NaGd(WO<SUB>4</SUB>)<SUB>2</SUB>:Eu<SUP>3+</SUP> phosphor were firstly reported. </LI> <LI> The CT band of Eu<SUP>3+</SUP> depends strongly on Eu<SUP>3+</SUP>-concentrations. </LI> </UL> </P>