Investigation On The Synthesis And Optical Properties Of Composite Oxide Upconversion Luminescence Materials

Upconversion luminescence materials doped with rare earth can produce visible light under the near-inferred laser excitation. Much attention has been paid to the research on the upconversion luminescence materials for their applications in many advanced technology fields, such as biomedical detecting, display, illumination and anti counterfeiting, and so on. Recently, the upconversion luminescence materials with the host of the composite oxide have become the focus of the investigation on the host for the upconversion luminescence materials because of their high upconversion efficiency and excellent chemical stability.In this paper, the composite oxide upconversion luminescence materials with general formula MRe(XO₄)₂ (M=Li, Na, K; X=W, Mo) and MRe₂(XO₄)₄ (M=Ba, Ca, Sr; X=W, Mo) have been synthesized by different methods. The optical properties and characteristics of structure of the as-prepared samples have been measured. The specific content of this manuscript is as follow: BaGd₂(MoO₄)₄: Yb³⁺, Er³⁺ and KGd(WO₄)₂: Yb³⁺/Ho³⁺/Er³⁺/Tm³⁺ phosphors have been prepared through high temperature solid state method, and the BaGd₂(MoO₄)₄: Yb³⁺, Er³⁺ sample has also been achieved by the sol-gel synthesis. Further, The Na0.5Gd0.5MoO₄: Yb³⁺, Tm³⁺ powders has been made by the hydrothermal method, and the MLa(MoO₄)₂: Yb³⁺, Tm³⁺ (M=Li, Na, K) and the NaLn(MoO₄)₂: Yb³⁺, Ho³⁺ (Ln=Gd, La, Y) phosphors have been synthesized through microwave sol-gel method and microwave combustion synthesis. The crystal structures and the particle surface features of all the as-synthesized powders have been characterized through XRD, SEM and TG-DTA. Besides, the upconversion luminescence spectra of the samples have been recorded under a 980 nm excitation, and how the upconversion luminescence intensities are affected by the various synthesized conditions and the different synthesis and ions in the host has been investigated in details. Moreover, the upconversion mechanisms of the phosphors doped with diverse rare earth ions have been discussed. It can be concluded that the upconversion luminescence of Ho³⁺ and Er³⁺ ions are produced through a two-photon process, while that of Tm³⁺ ion is through a three-photon process.