Optical thermometry using FIR of two close lying levels of different ions in Y2O3:Ho3+-Tm3+-Yb3+ phosphor

The possibility of combustion synthesized Ho3+-Tm3+-Yb3+ codoped Y2O3 phosphor as temperature sensor using fluorescence intensity ratio (FIR) technique under a 980 nm excitation has been reported. The variation in FIR of blue upconversion emissions generated from two closely spaced levels of the Tm3+ and Ho3+ ions ((1)G(4) and F-5(3)) as a function of temperature has been monitored up to 703 K. The maximum relative sensitivity has been found to be 3.38 x 10(-3) K-1 which indicates that the present phosphor material can play a vital role for high optical thermometric purpose. The results imply that the FIR of two closely spaced levels of two different rare earth ions can also be used as temperature sensor.