Synthesis, structural and temperature-sensing properties of nanosized Y2Ba3B4O12: Nd3+/Yb3+ phosphors

Abstract

This work involved the synthesis and characterization of the Y2Ba3B4O12 phase that has undergone various heat treatment periods and temperatures. This study concentrated on optical nanothermometry applications, with an emphasis on the near-infrared (NIR) spectrum and the temperature range of 25–55 °C to assess potential biological applications. The polymeric precursor method was used for the synthesis of Y2Ba3B4O12 nanoparticles co-doped with Nd3+ and Yb3+ with (0; 0.2; 0.5; 1.0 and 2.0) mol% treated at 1000 °C for 5 min, after the structural and spectroscopic thermal characterizations were performed. In order to confirm the heat treatment temperature (1000 °C for 5 min) for the production of crystalline phases, measurements employing thermal analysis (thermogravimetry and differential exploratory calorimetry) were used. The creation of the materials' pure phase was confirmed by the structural characterization performed using Raman spectroscopy and X-ray diffraction. Through Transmission Electron Microscopy it was possible to measure the size (∼110 nm) and different shapes of the particles and by electron diffraction the crystallite monocrystalline character was observed. We were able to analyze the doping ions' absorption bands using diffuse reflectance spectroscopy, to evaluate the high reflectance region of the matrix (areas where the pure matrix does not absorb), and to determinate the optical bandgap using the Kubelka-Munk equation. Additionally, it was examined how the fluorescence intensity ratios of Stark components changed as a function of temperature. In relation to the intensity ratio of the powder's emissions at 897 nm and 978 nm, the maximum sensor thermal sensitivity of 0.31%.°C−1 was determined.