New Strategy for Circumventing the Limitation of Thermally Linked States and Boosting the Relative Thermal Sensitivity of Luminescence Ratiometric Thermometry

Abstract

Optical ratiometric thermometry, based on the luminescence of trivalent rare-earth ions, has attracted considerable attention because of its noncontact working pattern, short response time, and strong antidisturbance ability. However, conventional optical thermal detection, on the basis of thermally linked states, has a relatively low relative sensitivity. To circumvent the limitation, here, a new strategy for boosting the relative thermal sensitivity, especially at relatively high temperatures, is introduced. It depends on two totally different mechanisms which own the contrary temperature dependences. For one thing, when excited at 310 nm, the green luminescence originating from CaWO4:Tb3+ phosphors increases monotonously because of the red shift of the charge-transfer band of the WO42– group. For another, this luminescence shows decreasing tendency gradually upon being directly excited at 380 nm. Thus, the intensity ratio between the luminescence obtained at two different excitation conditions is explo...