XPS study of Li/Nb ratio in LiNbO3 crystals. Effect of polarity and mechanical processing on LiNbO3 surface chemical composition

Скрылева, Е. А.; Кубасов, И. В.; Kiryukhantsev-Korneev, Ph. V.; Senatulin, B. R.; Жуков, Р. Н.; Zakutailov, K. V.; Малинкович, М. Д.; Parkhomenko, Yu. N.

doi:10.1016/j.apsusc.2016.07.108

Cited by 40 publications

(22 citation statements)

References 19 publications

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“…A direct comparison of the peak ratio is possible, since in Nb4s and Li1s the electrons originate in both cases from the S shell. 26 The increased ratio indicates a higher lithium content in the case where the NbO x layer is annealed with the cathode. As discussed earlier, this results in a strong decrease in interface resistance compared to as-deposited NbO x on annealed LCO (Fig.…”

Section: Resultsmentioning

confidence: 99%

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

Aribia

Sastre

Chen

et al. 2021

J. Electrochem. Soc.

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Protective coatings applied to cathodes help to overcome interface stability issues and extend the cycle life of Li-ion batteries. However, within 3D cathode composites it is difficult to isolate the effect of the coating because of additives and non-ideal interfaces. In this study we investigate niobium oxide (NbO x ) as cathode coating in a thin-film model system, which provides simple access to the cathode-coating-electrolyte interface. The conformal NbO x coating was applied by atomic layer deposition (ALD) onto thin-film LiCoO 2 cathodes. The cathode/coating stacks were annealed to lithiate the NbO x and ensure sufficient ionic conductivity. A range of different coating thicknesses were investigated to improve the electrochemical cycling with respect to the uncoated cathode. At a NbO x thickness of 30 nm, the cells retained 80% of the initial capacity after 493 cycles at 10 C, more than doubling the cycle life of the uncoated cathode film. Elemental analysis using TOF-SIMS and XPS revealed a bulk and surface contribution of the NbO x coating. These results show that in situ lithiated ALD NbO x can significantly improve the performance of layered oxide cathodes by enhancing interfacial charge transfer and inhibiting surface degradation of the cathode, resulting in better rate performance and cycle life.

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Section: Resultsmentioning

confidence: 99%

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

Aribia

Sastre

Chen

et al. 2021

J. Electrochem. Soc.

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“…Figure a shows that Bi is present as Bi 3+ , in which two binding energy peaks Bi 4f7/2 and Bi 4f5/2 of the typical Bi element for the BFO occur at 159.1 and 165.0 eV . As illustrated in Figure b, the presence of Fe 3+ is observed from two binding energy peaks Fe 2p3/2 and Fe 2p2/1 centered at 710.5 and 724.4 eV . In Figure c, the peak at 56.9 eV of Li 1s indicates that the existence of Li + .…”

Section: Resultsmentioning

confidence: 84%

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System

Cai

Yang

Liu

et al. 2019

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Photoelectrochemical carbon dioxide conversion to fuels such as carbon monoxide, methanol, and ethylene exhibits great potential to solve energy issues. Unfortunately, CO2 conversion efficiency is still low due to violent charge recombination at the photoanode. Herein, a novel 3D macroporous ferroelectric heterojunction composed of BiFeO3 and LiNbO3 is developed by a template‐assisted sol–gel method, aiming at facilitating charge transfer kinetics. As expected, a tremendous enhancement of photocurrent density (300 times vs bare planar BiFeO3 film) and charge transfer efficiency (up to 76%) is obtained in the HCO3−/CO2 system without any cocatalyst. The photoelectrochemical performance is switchable by poling to form a depolarization electric field. Photoelectrochemical impedance spectroscopy reveals that the charge transfer resistance decreases due to the synergistic effect of BiFeO3 3D macroporous skeleton and LiNbO3 passivation layer by tuning surface states. These results suggest a novel strategy for enhancing photoelectrochemical water oxidation as the anodic reaction of CO2 reduction.

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“…Through Gaussian fitting, there are three peaks in the high resolution XPS spectra of Li(1s)-Nb(4s), which are divided into peak1 (Nb 4s 62.2 eV), peak2 (Nb 4s 59.6 eV) and peak3 (Li 1s 55 eV), respectively. [34] As the ratio of Na/Li ratio increases, peak1 gradually increases and then becomes stable, peak2 gradually decreases and maintains stable, and peak3 gradually disappears. Notably, the chemical binding energy difference is contributed by the Fermi level shift, which is the evidence that the doped Na + ions make the crystal field environment change.…”

Section: Resultsmentioning

confidence: 96%

Effective Repeatable Mechanoluminescence in Heterostructured Li₁₋_xNa_xNbO₃: Pr³⁺

Yang

Liu

et al. 2021

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has been attracted to ML research by many groups around the world. According to the recovery performance of ML, it is generally believed that ML materials can be divided into trap-controllable and self-recoverable two modes. [9,10] The trap-controllable ML is associated with the captured carriers in shallow and deep traps at around below the conduction band or above the valence band. It relies on the induced energy releasing for the captured carriers from the traps, and it occurs for a certain level of mechanical stress (or strain) energy which is sufficient to activate the captured carriers releasing from the traps to recombine with emission centers, resulting in the ML phenomenon after removal the excitation source. [11,12] Self-recoverable ML materials are a special kind of luminescent materials, whose ML intensity can be output stable optical signals under the consecutive compressing-releasing cycles, and do not require light excitation to charge carriers. [13,14] Previous studies have shown that the self-recoverable ML materials depend on the generation of local piezoelectric fields, which promotes the process of electron-hole recombination and realizes the self-recoverable ML process. [15][16][17][18] However, either trap-controllable or self-recoverable ML still leads to some shortcomings. Trap-controllable mode is the current mainstream way to achieve ML, but its preirradiation process and relatively poor repeatability seriously affect the performance and accuracy of stress sensing. Self-recoverable mode can be considered as Mechanoluminescence (ML) is a striking optical phenomenon that is achieved through mechanical to optical energy conversion. Here, a series of Li 1−x Na x NbO 3 : Pr 3+ (x = 0, 0.2, 0.5, 0.8, 1.0) ML materials have been developed. In particular, due to the formation of heterostructure, the synthesized Li 0.5 Na 0.5 NbO 3 : Pr 3+ effectively couples the trap structures and piezoelectric property to realize the highly repeatable ML performance without traditional preirradiation process. Furthermore, the ML performances measured under sunlight irradiation and preheating confirm that the ML properties of Li 0.5 Na 0.5 NbO 3 : Pr 3+ can be ascribed to the dual modes of luminescence mechanism, including both trap-controllable and self-recoverable modes. In addition, DFT calculations further confirm that the doping of Na + ions in LiNbO 3 leads to electronic modulations by the formation of the heterostructures, which optimizes the trap distributions and concentrations. These modulations improve the electron transfer efficiency to promote ML performances. This work has supplied significant references for future design and synthesis of efficient ML materials for broad applications.

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XPS study of Li/Nb ratio in LiNbO3 crystals. Effect of polarity and mechanical processing on LiNbO3 surface chemical composition

Cited by 40 publications

References 19 publications

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System

Effective Repeatable Mechanoluminescence in Heterostructured Li₁₋_xNa_xNbO₃: Pr³⁺

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XPS study of Li/Nb ratio in LiNbO3 crystals. Effect of polarity and mechanical processing on LiNbO3 surface chemical composition

Cited by 40 publications

References 19 publications

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO3−/CO2 System

Effective Repeatable Mechanoluminescence in Heterostructured Li1−xNaxNbO3: Pr3+

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Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System

Effective Repeatable Mechanoluminescence in Heterostructured Li₁₋_xNa_xNbO₃: Pr³⁺