Ultrahigh-sensitive optical temperature sensing based on ferroelectric Pr3+-doped (K0.5Na0.5)NbO3

Optical temperature sensing based on the variation of the fluorescence intensity ratio of rare-earth materials has become appealing due to the multiple superiorities over the electrical temperature sensing. However, confined by the largest energy separation of two thermally linked levels of rare-earth ions, the highest sensitivity of such temperature sensing is essentially smaller than 2878/T-2, as reported previously from diverse systems. In this work, we demonstrate that ultrahigh-sensitive temperature sensing can be achieved from Pr3+-doped (K0.5Na0.5) NbO3 based on the intensity ratio of the D-1(2)-H-3(4) emission to the P-3(0)-H-3(4) emission. The ratio can be increased as high as 18-fold when temperature rises from room temperature to 456K, nicely fitting a thermally linked-levels-like equation and showing an ultrahigh sensitivity of 7997/T-2. The striking change of the ratio is attributed to the interaction between the two emission levels and the intervalence charge transfer state. This work may have provided a distinct route in the field of optical temperature sensing utilizing rare-earth-doped materials. In addition, the resultant product also possesses excellent photoluminescence and ferroelectric properties, showing promising potentials in multifunctional devices for practical applications. (C) 2016 AIP Publishing LLC.