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Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides
Published on: May 29, 2018
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Strong reciprocal interaction between polarization and surface stoichiometry in oxide ferroelectrics
Wissam A Saidi1, John Mark P Martirez, Andrew M Rappe
1Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
Nano Letters
|October 17, 2014
Summary
Polarization switchability in ferroelectric oxides like BaTiO3 and PbTiO3 offers new ways to control surface structure and composition. This research reveals ionic reconstructions as key to surface stability and nonstoichiometry.
Area of Science:
- Materials Science
- Surface Science
- Solid-State Chemistry
Background:
- Ferroelectric oxides such as Barium Titanate (BaTiO3) and Lead Titanate (PbTiO3) exhibit switchable polarization, crucial for electronic applications.
- Surface structure and stoichiometry significantly impact the properties of ferroelectric thin films.
- Understanding the interplay between polarization and surface phenomena is vital for device engineering.
Purpose of the Study:
- To systematically evaluate how polarization switchability affects the surface structure and stoichiometry of BaTiO3 and PbTiO3.
- To identify the driving forces behind surface stability in these ferroelectric materials.
- To explore novel mechanisms for controlling surface reconstructions and inducing nonstoichiometric compositions.
Main Methods:
- Computational modeling and simulation of BaTiO3 and PbTiO3 surfaces.
- Analysis of surface reconstructions and charge passivation mechanisms.
- Investigation of the influence of external factors like oxygen partial pressure on polarization switching.
Main Results:
- Charge passivation via ionic surface reconstructions is identified as the primary driver for surface stability.
- Varying substrate polarization provides a new route to control surface reconstructions and create nonstoichiometric structures.
- For thin films, the chemical environment, specifically oxygen partial pressure, can induce polarization switching and surface compositional changes.
- The calculated oxygen partial pressure for the positive-to-negative polar transition in PbTiO3 aligns with experimental data.
- BaTiO3 is found to be more resistant to polarization switching induced by oxygen control due to its lower reducibility.
Conclusions:
- Polarization switchability is a powerful tool for manipulating the surface structure and stoichiometry of ferroelectric oxides.
- Ionic surface reconstructions play a critical role in stabilizing ferroelectric surfaces.
- This work opens avenues for real-time control over the structure and composition of oxide surfaces, enabling advanced material design.
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