Speaker: Pro. Mariusz Stefański
Topic: Synthesis, structure and optical properties of nanocrystalline strontium cerium oxide
Date: April 18th, 2024 (Thursday)
Time: 10.00-11.00 a.m.
Venue: Room 428, School of Physics and Electronic Engineering
Sponsors: School of Physics and Electronic Engineering, Institute of Science and Technology
Biography:
He received a Master's degree in chemistry at the University of Wroclaw in 2011. Employed at the Institute of Low Temperature and Structure Research, Polish Academy of Sciences in Wroclaw since 2013. In 2018 he obtained a Ph.D. in chemical sciences in the same research unit. His scientific interests concern the preparation and optical characterization of micro and nanocrystalline inorganic phosphors. The main goal of his work is to investigate broadband anti-Stokes white emission induced by a concentrated laser beam operating in the near-infrared range (LIWE) generated from different hosts, as well as to study inorganic perovskites doped with lanthanides for use as luminescent solar concentrators. Co-author of 51 scientific publications published in international journals (H-index = 12) and one patent.
Abstract:
The main objective of the research is to develop the synthesis method of single-phase undoped and doped with selected lanthanide ions (Eu3+, Yb3+, or Nd3+) nanocrystalline cerium strontium oxide (Sr2CeO4) and investigate the mechanism of broadband anti-Stokes laser induced white emission (LIWE) observed from the system.
Sr2CeO4 is a very attractive material due to its unique optical properties. This host lattice demonstrates intensive charge transfer emission generated from Ce4+. Sr2CeO4 is characterized by high chemical stability and high luminescence efficiency.
Nanocrystalline Sr2CeO4 and Sr2CeO4:Ln3+ (Ln3+ = Eu3+, Yb3+, Nd3+) were prepared with Pechini’s technique. The phase purity of the obtained samples was confirmed by powder diffraction patterns. The spectroscopic properties of pure and Sr2CeO4:Eu3+ under Stokes excitation as a function of average grain size were investigated.
To generate LIWE the obtained materials were placed in the measurement chamber with vacuum inside. The samples were illumined by a focused infrared laser beam. It was shown that the intensity of white emission observed from nanocrystalline Sr2CeO4:Ln3+ exhibits threshold behavior and strong pressure dependence. Based on the obtained results, the mechanism responsible for the LIWE generation was proposed.