Nd3+ doped oxide thermal probes based on luminescence intensity ratio within BW-II and excitation in BW-I

Abstract

The Nd3+ have taken a central place in the field of nanothermometry thanks to the presence of several narrow Stark emission and is easily excited through the lasers commercially available. With the goal to boost the development of Nd3+-based nanothermometers, especially working with emissions into BW-II, the thermal response of different oxide matrices Y2O3, Y2Ge2O7, Y3Al5O12, YBO3, and Y3BO6 were evaluated considering emissions from the Nd3+ 4F3/2 → 4I11/2 transition, which falls into the BW-II. Interestingly, we observed these lines are more intense than those located in BW-I, which can enhance the signal-to-noise ratio. Therefore, the design of thermal probes emitting in BW-II showed to be an excellent strategy to provide more accurate thermal sensing as the scattering of the light by the tissues is reduced in BW-II. In light of this, we also maximized the luminescence intensity of the matrices by Nd3+ doping from 0.1 to 10 mol%. Furthermore, their structure and luminescence properties were investigated using X-ray diffraction, transmission electron microscope, diffuse reflectance spectroscopy, photoluminescence, and radiative decay curve measurements. Additionally, exploring thermal response and luminescence emission optimization in several compounds offers enriched information support to design new high-level Nd3+-based thermal probes. Among Y2O3, Y2Ge2O7, Y3Al5O12 (YAG), YBO3, and Y3BO6 matrices studied, Y2O3 is the promising matrix to conduct thermal sensing due to exhibiting the highest Sr value around 0.4 %.K−1 in which 0.5 mol% Nd3+ is the deal doping to maximize its luminescence intensity.