Synthesis and characterization of radioluminescent Pr3+-doped Bi2SiO5@SiO2 nanoparticles

Abstract

Nanostructured scintillators, or nanoscintillators, are very attractive alternatives to traditional scintillators because of their easily tunable size, shape and surface properties, ease of synthesis in aqueous solutions and superior optical and electromagnetic properties. This emerging technology is useful for a wide variety of fields, including medical imaging, nuclear security and waste management, astronomy and others. Herein, with the aim of developing a radioluminescent thermometer for high energy applications, the synthesis and characterization of a Pr3+-doped bismuth silicate inorganic radioluminescent nanoparticles (NPs) are discussed. A hydrothermal synthesis process was first used to obtain four batches of monodisperse Bi2O3 nanospheres, each with different Pr3+ content (0, 0.5, 1 and 2%). Subsequently, a Stöber synthesis was performed to coat their surface with a silica shell. The particles were later thermally treated to obtain Bi2SiO5:Pr3+@SiO2 nanospheres. The NPs’ morphology was investigated through SEM and AFM analyses, while their crystalline structure and crystallite size were probed by means of XRD analysis. Luminescence studies were performed by exciting both the Bi2SiO5 matrix and the Pr3+ ions directly, correlating the optical properties to the phase transition induced by doping. Luminescence lifetimes of the Pr3+ ion were also estimated. UV/visible reflectance spectra were taken for each batch to calculate the optical bandgap energy was through the Kubelka-Munk theory and Tauc plot. In addition, preliminary radioluminescent analyses were performed and temperature-dependent luminescence of a sample was tested to investigate the potential of the system as a thermal sensor.