Luminescence and preparation of Dy₂O₃ doped SrCO₃–WO₃–SiO₂ glass ceramics

Highlights

• Dy₂O₃ doped SrCO₃–WO₃–SiO₂ glass ceramics are synthesized.

• The optimum concentration of Dy³⁺ is found to be 1.6 mol.

• The reason of concentration quenching is dipole-dipole interaction.

• The maximum fluorescence lifetime is 796.5 μs.

Abstract

In this paper, Dy³⁺ doped SrCO₃–WO₃–SiO₂ glass ceramics are successfully prepared by melt-quenching method. The microscopic morphology, structure and luminescence properties of Dy³⁺ doped glass ceramics are investigated through XRD, DSC, SEM, photoluminescence spectra and decay curves etc. It can be determined that the crystalline phase is SrWO₄ after comparing with PDF normal card by XRD. Also, combining with the transmission curves, the optimum heat treatment temperature and time are 740 °C/1.5 h. In the emission spectrum, there are three obvious emission peaks at 484 nm, 575 nm and 665 nm, respectively. The optimum concentration of Dy³⁺ is found to be 1.6 mol, and electric multipole interaction is the main reason for the concentration quenching. The maximum fluorescence lifetime is 796.5 μs.

Introduction

Currently, the energy is on the verge of exhaustion, it is imperative to seek for proficient alternative for the replacement of conventional lighting, in order to protect the environment. The white light-emitting diode (w-LED) is a kind of new solid-state lighting, and the conventional w-LED is composed of a chip and phosphors coated on the surface. Furthermore, w-LED has become the best alternative lighting energy attributed to its characteristics of high energy efficiency, low loss, strong material stability and long service life [[1], [2], [3], [4]].

Tungstate, as a typical self-activated fluorescent matrix material, has a wide range of applications in the field of inorganic photoluminescence materials [5]. SrWO₄ has been reported to be an ideal host for rare-earth ions because of its thermal and chemical stability, strong absorption, low synthesis temperature and low environmental pollution. SrWO₄ is scheelite tetrahedral structure, WO₄²⁻ could transfer the absorbed energy to the doping rare earth ions to increase the luminescence intensity. Due to the electrons on the 2p energy level of the O atom transfer to the 5d energy level of the W atom, the charge transfer band is formed. Hence, the materials of the rare earth (RE) as activator incorporates SrWO₄ lattice can get some special colorful emission, which expected to be good photoluminescence materials [[6], [7], [8]]. As for the Dy³⁺ ion, it has three typical peeks which are blue, yellow and red emission. Moreover, Dy³⁺ ion based on their linear type f–f transitions, can emit narrow emissions in the visible range, resulting in high efficiency. As a result, Dy³⁺ doped materials have attracted more and more attention [[9], [10], [11], [12], [13], [14], [15]].

In the previous coverage, Dy³⁺ doped phosphors were widely studied, such as Sr₃GdNa(PO₄)₃F:Dy³⁺ [16], Ca₉Y(VO₄)₇:Dy³⁺ [17], LiBaPO₄:Dy³⁺ [18], which had excellent luminescence properties in white light region. However, the disadvantages of phosphors are the complex preparation process, higher cost, higher correlated color temperature (CCT>6000K) and the shorter lifetime. Consequently, in the purpose of obtaining the better w-LED, new materials should be synthesized which is provided with lower CCT and longer lifetime.

In order to overcome the shortcoming of phosphors, Dy³⁺ doped tungstate glass ceramics are considered to be promising white-emitting materials. In this experiment, Dy³⁺ doped transparent glass ceramics containing SrWO₄ crystal phase were firstly synthesized. The effects of different heat treatments on grain size and luminescence properties were investigated. The results proved that Dy³⁺ doped GCs had the potential application in w-LED.