Luminescence Thermometry Based on the Upconversion Luminescence from the Stark Sublevels of BaY2F8:Yb3+, Tm3+ Phosphor
A. K. Sharma, Govind B. Nair, S. J. Dhoble, R.E. Kroon, J.J. Terblans, H.C. Swart
Abstract
Abstract Visible and near-infrared (NIR) upconversion luminescence (UCL) emissions originating from the BaY 2 F 8 : Yb 3+ , Tm 3+ systems were investigated under a laser excitation at 980 nm. The BaY 2 F 8 :20 mol% Yb 3+ , x mol% Tm 3+ and BaY 2 F 8 : y mol% Yb 3+ , 0.5 mol% Tm 3+ phosphors showed prominent UCL at 800 and 810 nm. The optimized doping concentrations of Yb 3+ and Tm 3+ in the BaY 2 F 8 host matrix were evaluated, their spectroscopic properties were determined, and studies on their temperature-dependent behaviour were carried out. The temperature-sensing properties were studied by generating the fluorescence intensity ratio (FIR) of the UCL peaks originating from the thermally-coupled energy levels of the Tm 3+ ions. The Stark sublevels of 1 G 4 level of Tm 3+ ions were utilized to estimate the temperature-sensing abilities of the phosphor. Graphical Abstract