A self-calibrated luminescent thermometer based on nanodiamond-Eu/Tb hybrid materials

Luminescent hybrid materials based on nanodiamonds (NDs) and rare earth ions have been successfully synthesized by covalently modifying NDs with pyromellitic acid (PMA) which is capable of coordinating to Eu3+ and Tb3+ ions. With NDs acting as a host matrix, the PMA and rare earth ions serve as an organic sensitizer and activator, respectively, yielding a highly bright hybrid composite. Interestingly, for the co-doped hybrid composites ND-PMA-Eu/Tb, the intensity ratio of the two emissions, 5D4 → 7F5 transition (Tb3+) to 5D0 → 7F2 transition (Eu3+), is linearly related to temperature in the range from 77 K to 277 K. Therefore, the hybrid could be developed as a self-calibrated ratiometric luminescent thermometer due to its temperature-dependent luminescence performance.