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

Spasojevic, Irena; Sauthier, Guillaume; Caicedo, José Manuel; Verdaguer, Albert; Domingo, Neus

doi:10.1016/j.apsusc.2021.150288

Cited by 38 publications

(28 citation statements)

References 37 publications

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“…This assignment has been adopted several times, − but no study has yet provided a clear assignment between the binding energy (BE) of the peaks (high and low) and the position (exact depth) of the Ba atom. Besides this, other studies have attributed the high BE component to surface contamination, more particularly to BaCO 3 species. − Finally, some recent papers have rather associated this peak with Ba atoms in a higher oxidation state, namely corresponding to BaO 2 species. − To improve the understanding of BaTiO 3 surface and thus to be able to precisely study important characteristics of this system such as interaction with adsorbates or reactivity, it is essential to disclose unambigously the nature of the Ba 3d and 4d core level split in BaTiO 3 compounds.…”

Section: Introductionmentioning

confidence: 99%

Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study

et al. 2022

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In this paper, synchrotron radiation photoemission techniques are used to unravel the pending nature of the two Ba 4d components, also observed on Ba 3d lines, and commonly named Ba(α) and Ba(β). Investigations were carried out on the (001) surface of epitaxial very thin (≤20 nm) films combined with DFT calculations. Photoelectron diffraction experiments reveal different behaviors for Ba(α) and Ba(β) components. While six well-defined diffraction features corresponding to the BaTiO 3 bulk structure are observed for the Ba(α) component, no feature really appears in the diffraction pattern of Ba(β). This observations reveal the absence of forward scattering processes, hence this component comes mostly from surface BaO plane. Supporting these results, DFT calculations demonstrate a shift to lower binding energy (BE) only for the Ba 4d peak from the topmost BaO layer with respect to the photoelectron peak stemming from bulk layers. Hence, only one peak (the Ba(α) one) should be observed for a sample with a complete TiO 2 termination. This hypothesis is supported by photoemission measurements carried out at low photon energy in grazing angle emission, in order to enhance the signal from topmost layers with respect to the bulk. For each sample, the Ba(β)/ Ba(α) intensity ratio is well reproduced by a model where the Ba(β) signal is only coming from the topmost surface BaO plane.

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Section: Introductionmentioning

confidence: 99%

Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study

et al. 2022

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“…21 Concomitantly, polarization can also be affected by the photoinduced changes of surface state, which largely affect the internal field. [21][22][23][24][25] These potentially coexisting and entangled mechanisms challenge the fine control of ferroelectric polarization under illumination. Achieving the reversible rotation of the polarization sign by light using the listed mechanisms is not possible.…”

Section: Introductionmentioning

confidence: 99%

Control of up-to-down/down-to-up light-induced ferroelectric polarization reversal

et al. 2022

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“…[ 32 ] The BTO film was atomically flat, fully epitaxial and uniformly c ‐axis oriented with up‐polarized as‐grown state, as evidenced by piezoresponse force microscopy (PFM). [ 32 ] The writing speed experiments were performed using an Asylum MFP3D AFM with a fluid cell integrated to a low‐noise continuous flow humidity controller that by combining dry N 2 gas with distilled water allows high precision control of RH at the cell with long term stability. [ 33 ] The minimum value of RH achieved after exposure to pure N 2 gas for 60 h was 2.5%.…”

Section: Resultsmentioning

confidence: 99%

“…With this technique, XPS measurements were conducted in the range of RH between 0% and maximum of ≈17% (low and intermediate RH ranges) by increasing the water vapor pressure of the XPS chamber from UHV to 4 mbar. Obtained O 1s spectra were fitted following the model explained in detail in our previous works, [6,32] which enabled us to quantify the amount of molecular water adsorbed at every RH. The area of the molecular water peak normalized by the area of bulk oxide peak, which gives the information about the amount of water isothermally adsorbed on the surface, has been plotted as a function of RH and shown in Figure 3c.…”

Section: Effect Of Relative Humidity On the Writing Speed Of Ferroele...mentioning

confidence: 99%

Effect of Humidity on the Writing Speed and Domain Wall Dynamics of Ferroelectric Domains

Spasojevic

Verdaguer

Catalán

et al. 2021

Adv Elect Materials

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The switching dynamics of ferroelectric polarization under electric fields depends on the availability of screening charges in order to stabilize the switched polarization. In ferroelectrics, thin films with exposed surfaces investigated by piezoresponse force microscopy (PFM), the main source of external screening charges is the atmosphere and the water neck, and therefore relative humidity (RH) plays a major role. Here, it is shown how the dynamic writing of domains in BaTiO3 thin films changes by varying scanning speeds in the range of RH between 2.5% and 60%. The measurements reveal that the critical speed for domain writing, which is defined as the highest speed at which electrical writing of a continuous stripe domain is possible, increases non‐monotonically with RH. Additionally, the width of line domains shows a power law dependence on the writing speed, with a growth rate coefficient decreasing with RH. The size of the written domains at a constant speed as well as the creep‐factor μ describing the domain wall kinetics follow the behavior of water adsorption represented by the adsorption isotherm, indicating that the screening mechanism dominating the switching dynamics is the thickness and the structure of adsorbed water structure and its associated dielectric constant and ionic mobility.

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

Cited by 38 publications

References 37 publications

Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study

Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study

Control of up-to-down/down-to-up light-induced ferroelectric polarization reversal

Effect of Humidity on the Writing Speed and Domain Wall Dynamics of Ferroelectric Domains

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

Cited by 38 publications

References 37 publications

Nature of the Ba 4d Splitting in BaTiO3 Unraveled by a Combined Experimental and Theoretical Study

Nature of the Ba 4d Splitting in BaTiO3 Unraveled by a Combined Experimental and Theoretical Study

Control of up-to-down/down-to-up light-induced ferroelectric polarization reversal

Effect of Humidity on the Writing Speed and Domain Wall Dynamics of Ferroelectric Domains

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Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study

Nature of the Ba 4d Splitting in BaTiO₃ Unraveled by a Combined Experimental and Theoretical Study