Photonic Materials Laboratory of Kyoto University, Japan

Biography: Dr. Michele Back obtained both his B.Sc and M.Sc in Materials Science and he completed his Ph.D. degree cum laude in Chemical Sciences at Ca’ Foscari University of Venice, Italy (January 2017) in the field of optical materials. Currently, he is Post-doc (JSPS Fellow) at the Photonic Materials Laboratory of Kyoto University, Japan (Professor S. Tanabe).

His research interests include the design of bulk and nanoscale materials with advanced optical properties for applications in the fields of bioimaging, telecommunication and phosphors. At present his research is focused on the synthesis and characterization of bismuth-based luminescent materials and optical thermometers. He is author of 20 peer-reviewed publications and 2 international patents.

Speech Title: Luminescent Lanthanide doped Bi₂SiO₅/g-SiO₂ Core/Shell Nanocomposite for Biological and High Temperature Sensing

Aims: Sensing the temperature is a fundamental aspect for many applications in the biological and technological field. Taking advantage of the low temperature sealing ability of bismuth in glass, a new strategy for the design of high performance ceramic/glass core/shell nanocomposite consisting of lanthanide-doped Bi₂SiO₅/g-SiO₂ will be presented as a new class of thermal sensors.

Methods: By considering the reactivity between bismuth and silica, we choose a synthetic approach consisting in the growth of silica shell on lanthanide-doped Bi₂O₃ nanoparticles. The effect of the thermal treatments on the structural and morphological properties was analyzed by XRPD, SEM and TEM analyses while the temperature sensing ability of the systems were investigated by means of photoluminescence (PL) analysis.

Results: The fine control of the silica shell was demonstrated by comparing the experimental shell thickness obtained by SEM and TEM analysis and a simple theoretical model. The structural evolution of the system as a function of the temperature was investigated by means of TG-DSC and XRPD analyses. In addition, the lanthanide-doped orthorhombic Bi2SiO5 phase stabilized in the core of the nanocomposite was demonstrated to work as a ratiometric luminescent thermometer for the biological temperature range (290-350 K) but also at high temperature, up to 800 K.

Conclusions: The consistency of the synthetic procedure allowing to obtain tunable and monodisperse Ln-doped Bi₂SiO₅/g-SiO₂ core/shell nanoparticles are demonstrated to be suitable for the design of new ratiometric luminescent thermometers, working in a wide range of temperature (280-800 K).