Optical thermometry through green and red upconversion emissions in Er3+/Yb3+/Li+:ZrO2 nanocrystals

Variations of fluorescence intensity ratio of green (generated from Er3+ H-2(11/2) and S-4(3/2) levels) and red (generated from the sublevels of Er3+ E-4(9/2) level) upconversion emissions in Er3+/Yb3+/Li+:ZrO2 nanocrystals have been studied as a function of temperature under 976 nm laser diode excitation. In the temperature range of 323-673 K, the maximum sensitivities of about 0.0134 K-1 and 0.0104 K-1 are obtained by using green and red emission, respectively. Er-3+/Yb3+/Li+:ZrO2 nanocrystals show potential application value in nanoscale thermal sensor. (C) 2010 Elsevier B.V. All rights reserved.