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

Abstract

Eu3+-doped NaGd(WO4)2 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(WO4)2:Eu3+ phosphors. The results show that the Eu3+-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(WO4)2. The well-crystallized sheet-like NaGd(WO4)2 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 NaGd1-xEux(WO4)2 (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu3+ shifts to lower energy and broadens with increasing the Eu3+-concentration.