Dependence of upconversion emission and optical temperature sensing behavior on excitation power in Er3+/Yb3+ co-doped BaMoO4 phosphors

BaMoO 4 : Er 3+ /Yb 3+ phosphors with different concentrations have been fabricated by a facile hydrothermal method . The morphology observation shows that the shape and size of BaMoO 4 powders change after Er 3+ /Yb 3+ doping. The upconversion luminescence spectra consist of intense green bands centered at 536 and 558 nm and a weak red emission band peaked at 668 nm upon 980 nm excitation. The excitation power and doping concentration have little impacts on the color emitted from the samples. Applying the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors are investigated based on thermally coupled levels ( 2 H 11/2 and 4 S 3/2 ) and non-thermally coupled levels ( 4 F 9/2 and 4 S 3/2 ), respectively. The thermometry is sensitive to the excitation power for 4 F 9/2 and 4 S 3/2 levels, leading to large measurement errors caused by the power variation. Such a problem can be solved by using the power-insensitive FIR between 2 H 11/2 and 4 S 3/2 levels, which also shows the advantage of high absolute sensitivity with the maximum of 110.7 × 10 −4 K −1 . So, the developed BaMoO 4 :Er 3+ /Yb 3+ phosphors can be applied in green light upconverters, display devices and temperature sensors .