Constructing high sensitivity thermometry with dual-emitting Nd³⁺/Er³⁺/Yb³⁺ codoped BaWO₄ single crystal material

Inorganic oxides doped with rear earth(RE) have attracted much interest because of their outstanding optical properties. In this paper, the BaWO₄:Yb³⁺/Er³⁺/Nd³⁺ phosphors were successfully prepared by typical solid state method. The crystalline structure of the samples was characterized through X-ray diffraction(XRD). The morphology of that was demonstrated with field emission scanning electron microscopy(FE-SEM). Under 980 nm excitation, the BaWO₄: Yb³⁺/Er³⁺/Nd³⁺ phosphor presented four typical emissions at green(524-550 nm, Er³⁺), red(∼655 nm, Er³⁺), near infrared(∼710 nm, ∼820 nm, Nd³⁺). Furthermore, the temperature sensing properties of the samples were investigated in the temperature range of 303-573 K. The fluorescence intensity ratio(FIR) technique based on thermal and non-thermal coupled levels was applied to analyse the sensing performances. For BaWO₄:Yb³⁺/Er³⁺/Nd³⁺ phosphor, the maximum absolute sensitivity reached 0.0423 K^-1 at 303 K, which is based on ²H_11/2(Er³⁺) and ⁴F_7/2(Nd³⁺) levels. The repeatability of temperature response also was proved through four cold and heat cycles. The above result indicated that the BaWO₄:Yb³⁺/Er³⁺/Nd³⁺ phosphor would be a promising temperature sensing materials.