PCE 67/2017
Project Title: Doped oxide nanoparticles: From local structure to long range perspective via luminescence
Project Code: PN-III-P4-ID-PCE- 2016-0305
Contract Nr. : 67/2017
Project Funded by: UEFISCDI, Ministry of Education, Research, Youth and Sport, Romania
Period: 2017 - 2019
Project Leader: Carmen TISEANU
Contract Value: 850.000 RON
Project Summary
In the case of aliovalent doping, the misfit in the valence but also the ionic radii of the bulkier Ln dopants and host cations can lead to a complex distribution of Ln as isolated substitutional /interstitial centres or associates with defects (arising via charge compensation) and reduced solubility. So, the first question to be answered when studying lanthanide doped nanoparticles (NPs) is the following: How do we know if the nanoparticles have been successfully doped? To tackle this issue, we should turn to a powerful local structure technique. Since the dopants class is represented by the optically active Ln ions, a natural selection would be the luminescence spectroscopy based on use of Ln as luminescence probes. The project aims at clarifying the local structure around Ln dopants in three outstanding wide bandgap oxides SnO2, TiO2 and HfO2. As Ln dopants with local probe properties, we select the Eu, Sm, Tb, Dy and Er ions with relevant emission in the visible and near infrared, respectively. Our luminescence based on the simultaneous analysis of the site selective and time-gated luminescence allows an exceptional insight into the photophysics of doped NPs. The project will address also the current limitations existing in the literature and which regard, essentially, the correlation between the local structure and long - range properties. To this aim, we will correlate the in situ luminescence with in situ X ray diffraction and in situ Raman data to get in depth insight into the order/disorder, doping and surface effects during amorphous /crystalline to crystalline phase transition.
We believe that our luminescence based approach centred on the local structure analysis will give a better perspective on how to tackle the issue of doping Ln ions in wide bandgap oxide NPs and beyond. Integrating local and long range information into a unitary description of lanthanide doped nanoparticles via luminescence is certainly relevant for the vast majority of the lanthanide doped nanostructures. Since single or multiple functionalities of the oxide NPs are generally enhanced by the substitutional Ln doping, a more general understanding of the relationship between dopant − oxide and the desired property or application can be established. From the fundamental research side, the project is expected to enlarge our understanding of magnetic dipole emission of Ln ions.
Project Objectives:
The project aims at clarifying the local structure around lanthanide dopants in three outstanding wide bandgap oxides SnO2, TiO2 and HfO2. Our luminescence approach based on the simultaneous analysis of the site selective and time-gated luminescence allows an exceptional insight into the photophysics of doped nanoparticles. The project will address also the current limitations existing in the literature and which regard, essentially, the correlation between the local structure and long - range properties.