Preparation And Characterization Of Rare Earth-Doped Sodium Tungstate Powders

The upconversion luminescence phenomenon is used in a variety of technical fields,including biosensor arrays for biomolecule detection,DNA detection,biomarkers,laser media,solid state lighting,enhanced performance flat panel display panels and solar cell spectrum converters.In solid-state lighting and display technology,phosphors have a long history as luminescent materials.These are the main areas of potential use of upconverting luminescent applications and they have great potential benefits.In recent years,solid-state visible light sources have been used in incandescent and fluorescent light source systems.It has a variety of advantages and significant scientific and application values.In this paper,pure NYW and Re,Yb:NYW powders were synthesized by sintering at 800℃,900℃,1000℃,1100℃and 1200℃for 3 h using the high temperature solid phase method.The phase structure and morphology of powders were characterized and analyzed by XRD,TG-DSC,Raman spectroscopy,infrared spectroscopy and fluorescence spectroscopy.The results show that,a pure,stable NYW phase was obtained at 1000℃,the melting point of the NYW powder is determined,and the vibration information of the W-O bond is obtained.The luminescent properties of 1.5%Er,6%Yb:NYW powder,2.0%Ho,6%Yb:NYW powder,1.5%Tm,6%Yb:NYW powder were studied,strong blue,green,red light emission,and red,green light emission,and blue,red light emission were obtained respectively.Ho,Yb:NYW powder and Tm,Yb:NYW powders are two-photon transitions,and Er,Yb:NYW powder is a three-photon transition.The emission peaks of 1.5%Er,2%Ho,6%Yb:NYW powders are 526nm,549nm and 656nm.It may correspond to the transitions of ⁵F₄→⁵I₈,⁵S₂→⁵I₈ of Ho³⁺ion,or the transition of ⁴S_3/2→⁴I_15/2 of Er³⁺ion and the transition of ⁵F₅→⁵I₈ of Ho³⁺ion,or⁴F_9/2→⁴I_15/2 transition of Er³⁺ion.The emission peaks of 1.5%Er,1.5%Tm,and6%Yb:NYW powders are 479nm,528nm,548nm,and 657nm.It may correspond to the transition of ⁴F_7/2→⁴I_15/2,²H_11/2→⁴I_15/2,⁴S_3/2→⁴I_15/2 of the Er³⁺ion and the transition of ⁴F_9/2→⁴I_15/2 of the Er³⁺ion,or the transition of ¹G₄→³F₄ of Tm³⁺ions.The emission peaks of 2%Ho,1.5%Tm,6%Yb:NYW are 479nm,545nm and 656nm.It may correspond to the transitions of ⁵F₃→⁵I₈,³K₈→⁵I₈ of Ho³⁺ion,or the transitions of ¹G₄→³H₆ of Tm³⁺ion and the transitions of ⁵F₄→⁵I₈,⁵S₂→⁵I₈ of Ho³⁺ion,the transitions of ⁵F₅→⁵I₈ of Ho³⁺ion,or the transitions of ¹G₄→³F₄ of Tm³⁺ion.The emission peaks of 2%Ho,1.5%Tm,1.5%Er,6%Yb:NYW are 490nm,547nm and658nm.It may correspond to the ⁵F₃→⁵I₈,³K₈→⁵I₈ transitions of the Ho³⁺ion,or the¹G₄→³H₆ transitions of the Tm³⁺ion,or the ⁴F_7/2→⁴I_15/2 transition of the Er³⁺ion;the⁵F₄→⁵I₈,⁵S₂→⁵I₈ transitions of Ho³⁺ion and the ⁴S_3/2→⁴I_15/2 transition of Er³⁺ions;the⁵F₅→⁵I₈ transition of Ho³⁺ion,or the ⁴F_9/2→⁴I_15/2 transition of Er³⁺ion,or the¹G₄→³F₄ transition of Tm³⁺ion.