Modulation of luminescence thermometry in Nd3+-Yb3+ co-activated phosphors via engineering host matrix

Luminescence thermometry based on the rare earth (RE) doped materials has displayed promising applications in various fields due to its fast response and high spatial resolution. However, the achievement of sensitive and accurate temperature sensing over a wide temperature scope is still a great challenge for this thermal sensing technology. Herein, excited by 980 nm laser, the inverse thermal responses of the near-infrared emissions in Nd3+-Yb3+ codoped phosphors, which was attributed to the phonon-assisted energy transfer between RE ions, were employed for ratiometric thermometry within the temperature range of 303-773 K. The modification of thermometric capability for the NIR luminescence was proposed through engineering the aluminate host matrix with SiO2. The influence of SiO2 on the luminescence behaviors of Nd3+ and Yb3+ was systematically investigated through the X-ray diffraction patterns, Fourier-transform infrared spectra, Judd-Ofelt theory calculation, as well as luminescence decay profiles. The results demonstrated that the luminescence and the subsequent thermal sensing properties of Nd3+-Yb3+ ion pair were strongly dependent on the host. As the host structure varied from aluminate to aluminosilicate, the spontaneous radiative transition and the energy transfer for RE ions were clearly improved, whereas the multiphonon nonradiative relaxations were weakened. The Nd3+-Yb3+ codoped aluminosilicate phosphors synthesised by adding 100 mol% SiO2 exhibited much high sensitivity (0.7-4.6% K-1) at temperatures ranging from 303 to 773 K, accompanied with a measurement uncertainty of about 0.1 K. This work provides an effective guidance for developing high-performance luminescence-based ratiometric thermometers. (C) 2021 Published by Elsevier B.V.