Investigation by photoelectron spectro-microscopy of the interplay between surface chemistry and polarization landscape of ferroelectric surfaces


Project Director: Dr. Elena Laura Abramiuc

Project type: National
Project Program:  PD
Funded by:  Romanian National Authority for Scientific Research, UEFISCDI
Contractor:  National Institute of Materials Physics
Project Status: In progress
Start date:  04.08.2020
End date:  01.08.2022

The purposes of this project is to study by photoelectron spectroscopy with a spatial resolution as elevated as possible: (i) The stability of ferroelectric surfaces under X-rays and UV radiation fluxes, to test their suitability to be used as catalysts or photocatalysts. (ii) The suitability to use Pb-free cheap ferroelectrics, such as BaTiO3. (iii) To test model molecular reactions on a ferroelectric surface exhibiting a wide variety of different polarizations. The molecular reactions of interest will be: (a) CO oxidation; (b) CO reduction; (c) Fischer-Tropsch reactions involving carbon monoxide. The experiments will be performed by about 50 % in the National Institute of Materials Physics (NIMP) installations in Magurele and about 50 % using the synchrotron radiation facilities, mainly Elettra in Trieste, where NIMP also owns a setup installed on a beamline and has allocated beamtime for ‘in-house’ research and also on research based on proposals. The techniques that will be used to achieve the proposed objectives are: Photoelectron Spectromicroscopy, High Resolution Photoelectron Spectroscopy, Scanning Tunneling Microscopy and Spectroscopy, Scanning Photoelectron Microscopy, Low Energy Electron Diffraction, Mass Spectrometry. This project has two ambitious aims of comparable expected impact: (i) the first one is related to the validation of lead-free ferroelectric thin films as catalysts and photocatalysts for carbon monoxide based reactions (oxidation, reduction and Fischer-Tropsch); (ii) the second is related to the validation and improvement of the photoelectron spectromicroscopic method for analyzing not only the polarization landscape of ferroelectric surfaces, but also the spatio-temporal dynamics of reactions occurring on these surfaces.

  1. Study of the stability of ferroelectric surfaces, in order to use them further as catalysts.

Activities: 1.1 Write proposals for beamtime at SpectroMicroscopy and ESCA Microscopy (Elettra); 1.2 PZT and BTO samples synthesized by Pulsed Laser Deposition (PLD) on SrRuO3 (SRO) grown on (001) oriented SrTiO3 (STO) single crystals. After preparation, the samples will be structural and morphological checked by Atomic Force Microscopy, Scanning Electron Microscopy, High-Resolution Transmission Microscopy and X-ray Diffraction to evidence the epitaxial quality of the films. Piezoresponse Force Microscopy will be used to write micrometer size domains to be investigated in our Kratos system for XPS with spatial resolution; 1.3 X-ray Photoelectron Spectroscopy investigation on Kratos Surface Analysis and Surface Science Cluster.

 

  1. Testing model molecular reactions on PZT and/or BTO surfaces exhibiting different

polarisation states.

Activities: 2.1 The controlled  contamination of the PZT samples  with fatty acids; 2.2 Investigation of photocatalytic activity (under the influence of UV radiation); 2.3 Simultaneous CO oxidation and reduction reactions on areas with different polarization states; 2.4 Fischer-Tropsch reactions on PZT surface (2n + 1) H2 + n CO → CnH2n+2 + n H2O; 2.5 Investigation of the samples by XPS, STM, SPEM, SpectroMicroscopy before and after CO adsorption and desorption.

Project Director: Dr. Elena Laura Abramiuc  

Proiect Mentor : Dr. Cristian Mihail Teodorescu

Some of the results obtained in stage 1 following the measurement session at the ELETTRA synchrotron in Trieste on the SpectroMicroscopy line were sent to Applied Surface Science with title “Nanoscopic correlations from curve fitting of photoelectron spectromicroscopy data cubes of lead zirconate titanate films” being under revision.

In stage 2, a part of the results obtained at BESSY II Synchrotron on SMART Spectro-Microscope (UE49-PGM-SMART) were presented at the 13th International Conference on Physics of Advanced Materials (ICPAM-13).

Contact

Dr. Elena Laura Abramiuc

Senior researcher III

E-mail: stoflea.laura@infim.ro

Laboratory of Nanoscale Condensed Matter


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