Improved optical thermometry in Er3+:Y2O3 nanocrystals by re-calcination

Variations of fluorescence intensity ratio of green upconversion emissions in Er3+:Y2O3 nanocrystals and their bulk counterpart have been studied as a function of temperature. In the temperature range of 323-773 K, the maximum sensitivity of about 0.003 K−1 is obtained in the samples synthesized by the conventional sol-gel method at 800 °C. It is found that the upconversion emission is enhanced by a factor of about 56 after re-calcining the conventional samples at 1300 °C. Besides that, the sensitivity is increased to the value of about 0.004 K−1, and the sensing accuracy is also improved. With efficient upconversion luminescence, high degree of sensitivity and accuracy, Er3+ doped Y2O3 bulk counterpart show promising application in nanoscale thermal sensor.