Er3+-Yb3+ doped vanadate nanocrystals: A highly sensitive thermographic phosphor and its optical nanoheater behavior

Optical temperature sensors play a vital role in biomedical and therapeutic applications due to their reliable and unique detection sensitivity. Internal self-heating in Er3+/Yb3+ doped yttrium vanadate particles is observed on optical excitation at 980 nm wavelength of a diode laser. Temperature sensing performance is investigated by exploiting the temperature dependent fluorescence intensity ratio (FIR) of two emission bands (2H11/2/4S3/2 → 4I15/2) of Er3+ ion. The calculated sensor sensitivity, 0.01169 K−1 at 380 K, is found highest among the reported results for inorganic nanosensors. The temperature of the nanocrystalline sample particles is found to increase by a large value (315-460 K) within a short interval of excitation pump power (13.18-50.45 W cm−2). This achievement suggests potential use of the present material as an optical nanoheater for hyper-thermal treatment.