SCIENTIFIC HIGHLIGHTS

Oxidation processes at the surface of BaTiO3 thin films under environmental conditions
02 July 2021
Dissociation and adsorption of water on ferroelectric oxide surfaces play important role in the processes of screening and switching dynamics of ferroelectric polarization, as well as in catalytic processes which can be additionally coupled with light, temperature or vibration stimuli. In this work, we present XPS study of ferroelectric BaTiOthin films and determine the entanglement between surface chemistry, polarization direction and stability, by observing changes upon time exposure to environmental conditions, heating in Oatmosphere and irradiation in vacuum.
We devote special attention to Ba 3d spectral region and identify two different oxidation states of O atoms in the compounds of Ba. While this second specie was generally attributed to Ba in surface compounds where it has different oxygen coordination than in the bulk, based on the XPS results of oxygen annealed thin films, we demonstrate that this so far neglected component, corresponds to barium peroxide (BaO2) and identify it as important active specie for the study of screening mechanisms closely related with catalytic activity present in this ferroelectric material. Finally, we report on chemically assisted polarization switching in thin films induced by heating in vacuum or exposure to X-Ray radiation due to the formation of positive surface electric field created by oxygen or electron vacancies, respectively.
Hits: 370
Tuneable and low cost molecular electronics

Oxidation processes at the surface of BaTiO3 thin films under environmental conditions


I. Spasojević, G. Sautier, J. Caicedo, A. Verdaguer, N. Domingo

Applied Surface Science, 2021, 150288, ISSN 0169-4332,
https://doi.org/10.1016/j.apsusc.2021.150288

Also at ICMAB

  • From high quality packing to disordered nucleation or phase separation in donor/acceptor interfaces: ClAlPc-C60 on Au(111)

    Information
    03 September 2021 183 hit(s) Molecular
    The dramatic consequences that the orientation adopted by the molecular dipoles, in diverse arrays of chloroaluminum phthalocyanine (ClAlPc) on Au(111), have on the ulterior adsorption and growth of C60 are explored by means of an all scanning probe microscopy approach. The unidirectional downwards organization of the molecular dipoles at the first layer reduces charge transfer from the metal to C60. Imbalance between attractive and repulsive interactions of the fullerenes are crucial for their ordered supramolecular aggregation.
  • Synthesis of 2D Porous Crystalline Materials in Simulated Microgravity

    Information
    27 August 2021 243 hit(s) Molecular
    To date, crystallization studies conducted in space laboratories, which are prohibitively costly and unsuitable to most research laboratories, have shown the valuable effects of microgravity during crystal growth and morphogenesis. Herein, an easy and highly efficient method is shown to achieve space-like experimentation conditions on Earth employing custom-made microfluidic devices to fabricate 2D porous crystalline molecular frameworks.
  • Rich Polymorphism of Layered NbS3

    Information
    20 August 2021 262 hit(s) Molecular
    Layered group V transition-metal trichalcogenides are paradigmatic low-dimensional materials providing an ever increasing series of unusual properties. They are all based on the same basic building units, one-dimensional MX3 (M = Nb, Ta; X = S, Se) trigonal-prismatic chains that condense into layers, but their electronic structures exhibit significant differences leading to a broad spectrum of transport properties, ranging from metals with one, two, or three charge density wave instabilities to semimetals with potential topological properties or semiconductors.
  • Red light-emitting Carborane-BODIPY dyes: Synthesis and properties of visible-light tuned fluorophores with enhanced boron content

    Information
    17 August 2021 281 hit(s) Molecular
    A small library of 2,6- and 3,5-distyrenyl-substituted carborane-BODIPY dyes was efficiently synthesized by means of a Pd-catalyzed Heck coupling reaction. Styrenyl-carborane derivatives were exploited as molecular tools to insert two carborane clusters into the fluorophore core and to extend the π-conjugation of the final molecule in a single synthetic step.
  • A Trapezoidal Octacyanoquinoid Acceptor Forms Solution and Surface Products by Antiparallel Shape Fitting with Conformational Dipole Momentum Switch

    Information
    06 August 2021 297 hit(s) Molecular
    A new compound formed by two antiparallelly disposed tetracyano thienoquinoidal units has been synthesized and studied by electrochemistry and several spectroscopic techniques. Its self-assembly on a Au(111) surface has been investigated by scanning tunneling microscopy.

INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA, Copyright © 2020 ICMAB-CSIC | Privacy Policy | This email address is being protected from spambots. You need JavaScript enabled to view it.