Optical temperature sensing behavior of enhanced green upconversion emissions from Er-Mo:Yb2Ti2O7 nanophosphor

The Er-Mo:Yb2Ti2O7 nanocrystalline phosphor has been prepared by sol-gel method and used as an optical thermometry. By Mo codoping, the green upconversion (UC) emission intensity increased about 250 times than that of Er:Yb2Ti2O7 under a 976 nm laser diode excitation. It indicates that such green enhancement arises from the high excited state energy transfer (HESET) with the (IF7/2)-F-2, T-3(2)> state of Yb3+-MoO42- dimer to the F-4(7/2) level of Er3+. The fluorescence intensity ratio (FIR) of the two green UC emissions bands was studied as a function of temperature in a range of 290-610K, and the maximum sensitivity and the temperature resolution were approximately 0.0074 K-1 and 0.1 K, respectively. It suggests that the Er-Mo:Yb2Ti2O7 nanophosphor with a higher green UC emissions efficiency is a promising prototype for applications in optical temperature sensing. (C) 2011 Published by Elsevier B.V.