From 2D to 3D+ nanoscale characterization of advanced functional materials


Project Director: Dr. Corneliu Ghica
Project ID: PN-III-P4-ID-PCE-2016-0529
Project Director: Dr. Corneliu Ghica
Project Type: National
Project Program: PNIII - P4: Fundamental and Frontier Research
Funded by: Romanian National Authority for Scientific Research, UEFISCDI
Project Status: In progress

 

Project abstract

In materials science, when designing and investigating the chemo-physical properties of new materials the sine qua non starting point is represented by the necessity to identify, understand and control the microstructure of the examined material. Nanosciences and nanotechnology require manipulating nano-objects or even individual atoms, which requires complementary spectroscopic, diffraction and imaging techniques able to provide information at nanometric scale or below. One of the major challenges today in designing and engineering nanoscale functional materials is the complex 3D characterization on a nanometric scale. Electron tomography represents the only reliable technique to provide 3D morphological, structural and analytical information at nanometric scale. In our country we are now able to perform state-of-the-art analytical microstructural investigations by HRTEM, STEM and EELS, including atomic resolution elemental mapping or direct visualization of light atomic species. Electron tomography has been only introduced and developed in the field of life sciences, being currently applied in cellular biology, while electron tomography in materials science is not yet present. The scientific motivation of this project is to open the way at the national level towards electron tomography in materials science as a new dimension in the microstructural characterization of the advanced functional materials. The project will be focused on metal oxide semiconductors (MOS) functional materials to be used as gas sensors for environmental monitoring. Along with complementary spectroscopic techniques (EELS, XPS, EPR) the project will create a complete “3D+” insight (3 spatial + 1 spectroscopic dimensions) into the fine chemo-physical processes at nanometric scale in order to reveal and understand the connection between the 3D microstructural/spectroscopic properties and the functionality of the MOS gas sensing systems.

 

Project Objectives

General objective

Contribution to the development of the field of electron microscopy in Romania

Specific objectives

1. Revealing 3D morphology of mesoporous MOS-NP systems by nanoscale electron tomography.

2. Correlation between the 3D morphology, 2D microstructural and spectroscopic information and the gas sensing properties of the MOS-NP systems.

NamePositionTask
Corneliu GHICASenior researcher  1

Project manager

Project management, HRTEM, STEM, EELS, e-tomography, results dissemination
Valentin Serban TEODORESCUSenior researcher 1TEM, electron diffraction, in-situ TEM,  results dissemination
Simona SOMACESCUSenior researcher 2Chemical synthesis, XPS measurements,  results dissemination
Daniela GHICASenior researcher 2X-band EPR measurements, data processing, results dissemination
Adelina STANOIUSenior researcher 2Electrical measurements under controlled atmosphere, statistics and modeling of the experimental results, results dissemination
Raluca Florentina NEGREAScientific researcherSTEM, EELS, e-tomography, image simulation, results dissemination
Ionel Florinel MERCIONIUScientific researcherMorpho-structural and compositional characterization by  SEM, EDS, results dissemination
Ioana Dorina VLAICUScientific researcherChemical synthesis,  results dissemination
Andrei Cristian KUNCSERScientific researcherEFTEM, STEM, e-tomography,  results dissemination
Cosmin Marian ISTRATEScientific researcher assistant, PhD studentTEM, STEM, EELS, results dissemination
Mariana STEFANSenior researcher 2Q-band EPR measurements, data processing, results dissemination
Cristian Eugen SIMIONSenior researcher 3Electrical measurements under controlled atmosphere, results dissemination
Valentin Adrian MARALOIUSenior researcher 3TEM/HRTEM, EDS, EELS, results dissemination
Aurel Mihai VLAICUSenior researcher 3SEM-FIB processing, XRD, data processing

Project stage 1 - Preliminary activities of synthesis and characterization of the MOS-NP systems regarding the mesoporous structure, nature and quantity of the deposited material on the surface.

Performed activities

  1. Preparation of the mesoporous metal oxide semiconductor (MOS) structures and their decoration with catalytic nanoparticles (MOS-NP systems) by solvothermal synthesis from polymeric precursors and wet impregnation method. Mesoporous structures of SnO2, SnO2:Zn and SnO2:In decorated with Pd/Fe based nanoparticles have been prepared.
  2. Preliminary evaluation of the synthesized MOS-NP systems by XRD, SEM, EDS techniques, from a structural, morphological and compositional point of view. The formation of nanostructured tetragonal phase of SnO2 (cassiterite) has been evidenced by XRD. The mean grain size varies between 5-10 nm, depending on the doping level. Our measurements evidenced that in general, doping inhibits the crystal growth, resulting in nanoparticles with a lower size. SEM-EDS shows that palladium, as decorating element, is segregated in clusters of nanoparticles of 100-200 nm presumably embedded into the mesoporous SnO2 matrix.
  3. Microstructural and spectroscopic properties of the MOS-NP systems spatially resolved by HRTEM, STEM, EFTEM, EELS, EDS. Transmission electron microscopy confirms the formation of the tetragonal SnO2 phase consisting in nanocrystals with a mean size in the range 5-10 nm, depending on the sample. STEM-EDS observations have proven that doping with Zn or In is uniform at nanometric level, while Pd is non-uniformly distributed, forming clusters of tens or hundreds of nm size.
  4. 3D morphology at nanometric scale by electron tomography: optimizing the acquisition parameters of the tomographic series. Series of tomographic images have been acquired showing that the Pd clusters are actually attached to the surface of large mesoporous grains of SnO2.
  5. Complementary spectroscopic characterization of surface and volume properties by XPS and EPR. XPS measurements evidenced the surface oxidation of the Pd-rich nanoparticles. EPR measurements have evidenced the presence of several types of point defects, such as a substitutional N center or substitutional Mn2+ center (in the case of the Zn-doped samples).

 

Project stage 2 – Advanced 3D+ morpho-structural characterization of MOS-NP systems

Performed activities

  1. Fine tuning of the synthesis parameters for the increase of the specific surface area and the uniform dispersion of the Fe/Pd-based nanoparticles. Two synthesis routes have been applied for fabricating mesoporous supports from SnO2 (pure or doped with In) using either organic or inorganic precursors and two types of surfactants (Brij 52 or CTAB). Wet and semi-dry impregnation methods have been used for decorating the mesoporous SnO2-based supports with Pd or Fe-based nanoparticles.
  2. Global structural, morphological and compositional evaluations by XRD, SEM and EDS measurements. The formation of nanostructured tetragonal phase of SnO2 (cassiterite) has been evidenced by XRD. The mean grain size varies between 4-16 nm, depending on the doping level, type of surfactant and thermal treatment. Our measurements evidenced that in general, doping (with Zn or In) inhibits the crystal growth, resulting in nanoparticles with a lower size. SEM-EDS shows that palladium, as decorating element, is segregated in clusters of nanoparticles of 100-200 nm presumably embedded into the mesoporous SnO2 matrix. However, SEM-EDS measurements onto Fe decoration by semi-dry impregnation reveals a more uniform distribution of Fe with respect to the SnO2 matrix.
  3. Surface and volume distribution of the metallic ions by EPR spectroscopy in correlation with XPS measurements. Measurements of EPR spectroscopy at variable temperature have evidenced the presence of NO radicals adsorbed onto Sn4+ cationic positions. The Zn-doped samples reveal the presence of Mn2+ centers as non-intentional doping element (traces below 0.01%) usually associated with zinc. High-resolution XPS measurements have evidenced 3 valence states for Pd: metallic Pd, Pd2+ and Pd4+.
  4. Study of the morphological and structural stability of the synthesized MOS-NP systems at variable temperature by in situ heating TEM experiments. In situ heating has been performed during the TEM observations up to 600 oC. Although no structural modifications have been evidenced, morphological changes do occur at temperatures above 500 oC concerning the aggregation of the Pd-rich decorating nanoparticles.
  5. Nanoscale 3D reconstruction and by electron tomography of the mesoporous MOS-NP systems (part 1). The 3D reconstruction procedure has been optimized using several algorithms (Weighted Back-Projection - WBP, Simultaneous Iteration Reconstruction Technique - SIRT and Simultaneous Algebraic Reconstruction Techniques - SART). The procedure has been applied to reveal the morphological relation between the Pd-rich decorating nanoparticles and the SnO2 mesoporous support.

 

Project stage 3 – Connection between the morphological, structural, spectroscopic and gas sensing properties

Foreseen activities

  1. . Fabrication of gas sensors and the characterization of their electrical properties under controlled atmosphere of NO2, ethanol or CO.
  2. 3D reconstruction and nanoscale modeling by electron tomography on heterogeneous mesoporous MOS-NP systems.
  3. Correlation between the nanoscale 3D information and the atomic structure of the nanoparticles obtained by TEM/HRTEM investigations and electron tomography.
  4. Connection between the spectroscopic information at atomic level and the global information from the EPR, XPS, EELS and EDS measurements.
  5. Understanding the growth and assembling mechanisms of the heterogeneous mesoporous MOS-NP systems from the 3D morphological, microstructural and spectroscopic investigations in relation with the methods and parameters of chemical synthesis.
  6. Chemical and physical sensing mechanisms resulting from the nanoscale 3D, microstructural and spectroscopic information on the MOS-NP systems in connection with their electrical properties under controlled atmosphere.
  7. Dissemination

Cosmin Marian ISTRATE

6-9 February 2018 - Attended the courses of the FELMI/European EELS & EFTEM School organized by FELMI-ZFE, Graz University of Technology, Austria

Aurel Mihai VLAICU

26-30 November 2018 - Attended the courses of the international school Materials Characterization by the Combined Analysis MAUD 2018 organized by University of Trento, Italy

Cosmin Marian ISTRATE

01.10.2018 - was admitted as PhD student at the University of Bucharest, Faculty of Physics, with the thematic “Local structural and spectroscopic information in nanostructured materials ”, under the supervision of Dr. Valentin Serban Teodorescu

List of Publications:

 

Papers

 

1. Gas sensing properties of NiO/mesoporous SnO2

A. Stanoiu, S. Somacescu, C.E. Simion, Jose Maria Calderon-Moreno, O.G. Florea

IEEE Xplore Digital Library, DOI: 10.1109/SMICND.2017.8101166

Proceedings of International Conference of Semiconductors 2017 (CAS), 93-96 (2017)

http://ieeexplore.ieee.org/document/8101166/

2. Networked mesoporous SnO2 nanostructures templated by Brij (R) 35 with enhanced H2S selective performance

Stanoiu, C. E. Simion, A. Sackmann, M. Baibarac, O. G. Florea, P. Osiceanu, V. S. Teodorescu, S. Somacescu,

Microporous and Mesoporous Materials 270, 93-101 (2018)

3. Bimodal mesoporous NiO/CeO2-δ-YSZ with enhanced carbon tolerance in catalytic partial oxidation of methane—Potential IT-SOFCs anode

M. Florea, N. Cioatera, P. Osiceanu, J. M. Calderon-Moreno, C. Ghica, F. Neatu, S Somacescu

Applied Catalysis B: Environmental 241, 393–406 (2019)

4. Nanoclustered Pd decorated nanocrystalline Zn doped SnO2 for ppb NO2 detection at low temperature

Somacescu, C. Ghica, C. E. Simion, A. C. Kuncser, A. M. Vlaicu, M. Stefan, D. Ghica, O. G. Florea, I. F. Mercioniu and A. Stanoiu

Sensors and Actuators B: Chemical 294, 393-406 (2019)

5. Tailoring the Dopant Distribution in ZnO:Mn Nanocrystals

D. Vlaicu, D. Ghica, M. Stefan, A. V. Maraloiu, A. C. Joita, C. Ghica

Scientific Reports 9, 6894 (2019)

6. Low temperature CO sensing under infield conditions with In doped Pd/SnO2

A. Stanoiu, C. Ghica, S. Somacescu, A. C. Kuncser, A. M. Vlaicu, I. F. Mercioniu, O. G. Florea, C. E. Simion

Sensors and Actuators B: Chemical, submitted (manuscript no.: SNB-S-19-05856-1)

 

Conferences

 

1. Gas sensing properties of NiO/mesoporous SnO2,

Stanoiu, S. Somacescu, C.E. Simion, Jose Maria Calderon-Moreno, O.G. Florea,

International Semiconductor Conference CAS 2017,  October 11-14, 2017, Sinaia, Romania

Oral presentation

 

2. Gas sensing mechanism involved in H2S detection with NiO loaded SnO2 gas sensors

C.E. Simion, O.G. Florea, A. Stanoiu

International Semiconductor Conference CAS 2017, October 11-14, 2017, Sinaia, Romania

Oral presentation

 

3. Analytical TEM/STEM Investigations of Ion Tracks in CaF2: Facts and Doubts

C. Ghica, R. F. Negrea, M. Karlušić, Z. Siketić, M. Jakšić, M. Schleberger and S. Fazinić

9th International Conference on Nanomaterials - Research & Application NANOCON 2017, October 18-20, 2017, Brno, Czech Republic

Oral presentation

 

4. Microstructural characterization of BNT-BT ferroelectric thin film by advanced TEM techniques

C. M. Istrate, R. F. Negrea

9th International Conference on Nanomaterials - Research & Application NANOCON 2017, October 18-20, 2017, Brno, Czech Republic

Poster

 

5. Microstructural and analytical investigations of SnO2 nanowires for gas sensing applications

V.A. Maraloiu, C. Ghica, D. Zappa, E. Comini

9th International Conference on Nanomaterials - Research & Application NANOCON 2017, Brno, Czech Republic, October 18-20, 2017

Poster

 

6. Tailoring the Dopant Distribution in ZnO:Mn Nanocrystals

D. Ghica, I. D. Vlaicu, M. Stefan, V. A. Maraloiu, C. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania

 

7. On the thermal stability of mesoporous metal oxide systems decorated with metallic nanoparticles for gas sensing applications

M. C. Istrate, V. A. Maraloiu, C. Radu, I. D. Vlaicu, S. Somacescu, A. Kuncser, C. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania

 

8. 3D Perspectives on SnO2 based systems for gas sensing devices

A. C. Kuncser, M. C. Istrate, V. A. Maraloiu, C. Radu, I. D. Vlaicu, S. Somacescu, C. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania

 

9. Influence of Zr Concentration on the Morphology and Structure of BaTi1-YZryO3 Particles

V. A. Maraloiu, I. D. Vlaicu, M. M. Maček Kržmanc, I. Mercioniu, D. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania

 

10. Characterization of ceramic layers for thermal barriers coatings

I. Mercioniu, A.M. Vlaicu, C. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania

 

11. Nanometric morpho-structural characterization of mesoporous metal oxide semiconductors for chemo-resistive gas sensors

C. Mihalcea, A. C. Kuncser, I. F. Mercioniu, A. M. Vlaicu, S. Somacescu, C. Ghica

3-rd Conference of the Romanian Electron Microscopy Society, October 23-25, 2019, Poiana Brasov, Romania


PROJECTS/ NATIONAL PROJECTS


Back to top

Copyright © 2022 National Institute of Materials Physics. All Rights Reserved