Microwave-assisted hydrothermal synthesis and laser-induced optical heating effect of NaY(WO_4)_2:Tm^3+/Yb^3+ microstructures

Tm3+/Yb3+ codoped NaY(WO4)2 microstructures with various Tm3+ concentrations and 10 mol% Yb3+ concentration and 1 mol% Er3+/10 mol% Yb3+ codoped NaY(WO4)2 microstructure were prepared via a microwave-assisted hydrothermal reaction. The crystal structure and microscopic morphology of the products were characterized by means of XRD and FM-SEM. Er3+/Yb3+ doped NaY(WO4)2 microstructure was used as temperature sensing probe for studying on the laser heating behavior in Tm3+/Yb3+ doped NaY(WO4)2 microstructures. It was found that higher laser excitation density resulted in higher sample temperature, and the sample with higher Tm3+ doping concentration exhibited more obvious heating effect when excited by 980 nm laser. Moreover, the time scanning upconversion spectra displayed that the upconversion luminescence intensities for both the samples with low and high Tm3+ concentrations almost unchanged with 980 nm laser irradiation time when the excitation power density was lower, but decreased greatly when the excitation power density was higher, and the sample with low Tm3+ concentration displayed larger luminescence intensity change rate. This phenomenon was explained by Arrhenius’s model for the thermal quenching process.