Dislocation-enhanced electrical conductivity in rutile TiO2 accessed by room-temperature nanoindentation

Bishara, Hanna; Tsybenko, Hanna; Nandy, Supriya; Muhammad, Qaisar Khushi; Frömling, Till; Fang, Xufei; Best, James P.; Dehm, Gerhard

doi:10.1016/j.scriptamat.2022.114543

Cited by 16 publications

(12 citation statements)

References 39 publications

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“…With microcontacts, only a small volume below the electrode is probed, which provides the opportunity to investigate the local electrical conductivity of dislocations in terms of spreading resistance . This allows elucidating the dislocations’ impact much better than the bulk measurements, as dense dislocation regions can be discriminated from dislocation-deficient regions on the same sample. , Figure A provides an SEM image with a dense ⟨110⟩{110} dislocation field (similar to Figure D), along with the schematics of circular microelectrodes placed onto the dislocation field and the region away from it (for actual microelectrodes’ configuration see Figure S5A in the SI). Temperature-dependent impedance investigations revealed an increase in the electrical conductivity due to the presence of a high dislocation density by roughly a factor of 3 .…”

Section: Resultsmentioning

confidence: 99%

Dislocation-Mediated Oxygen–Ionic Conductivity in Yttria-Stabilized Zirconia

et al. 2022

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Yttria-stabilized zirconia (YSZ) has become an indispensable solid electrolyte material in modern solid oxide fuel and electrolysis cells (SOFCs/SOECs) as well as oxygen sensors. The oxygen ionic conductivity of YSZ is among the highest known so far. For energy efficiency optimization of SOFCs and lowering the high-temperature degradation of electrodes, the oxygen ionic conductivity needs to be further enhanced. This would allow for a reduction in application temperature. Despite extensive regular point defect-doping strategies, this key issue remains unsolved. Here, we investigate the role of mechanically induced dislocations (line-defects) on electrical conductivity and oxygen transport in bulk YSZ. An advanced mechanical deformation approach is employed to generate distinctly aligned dislocation-rich and -deficient regions. The in-depth electrical characterization of these regions exhibited highly conducting effects of dislocation-induced strain inside the bulk material. Furthermore, targeted oxygen tracer diffusion experiments prove enriched oxygen incorporation within the dislocation bundles. Therefore, the potential of mechanically induced dislocations is elucidated as a design element to tune the bulk ionic transport in YSZ.

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Section: Resultsmentioning

confidence: 99%

Dislocation-Mediated Oxygen–Ionic Conductivity in Yttria-Stabilized Zirconia

et al. 2022

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“…When the ball-milling time is extended to 12 h, the impedance value changes obviously. This is mainly due to the existence of more dislocation defects in the particles caused by the long-time ball milling, which reduces the transmission resistance of electrons and reduces the impedance value [ 11 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Cathode Physical Properties on the Preparation of Fe3Si0.7Al0.3 Intermetallic Compounds by Molten Salt Electrode Deoxidation

Liang

et al. 2022

Materials

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As a new process, molten salt electrolysis is widely used in the preparation of metal materials by in situ reduction in solid cathodes. Therefore, it is meaningful to study the influence of the physical properties of solid cathodes on electrolysis products. In this paper, mixed oxides of Fe2O3-Al2O3-SiO2 were selected as raw materials, and their particle size distribution, pore size distribution, specific surface area, and other physical properties were investigated by mechanical ball milling at different times. The CaCl2–NaCl molten salt system was selected to electrolyze the sintered cathode solid at 800 °C and a voltage of 3.2 V. The experimental results show that with the prolongation of ball-milling time, the particle size of mixed oxide raw materials gradually decreases, the specific surface area gradually increases, the distribution of micropores increases, and the distribution of mesopores decreases. After sintering at 800 °C for 4 h, the volume and particle size of the solid cathode increased, the impedance value gradually decreased, and the pores first increased and then decreased. The electrolysis results showed that the prolongation of the ball-milling time hindered the electrolysis process.

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“…60,77,78 However, this is still rather a qualitative investigation, as we do not have a fully homogeneous phase with constant resistivity below the ME. 60,79 This means that the measured resistance depends on the density and the extent of the dislocation network below the electrode. The large back surface was used as the CE.…”

Section: Local Electrical Investigations (Microcontact Electrochemica...mentioning

confidence: 99%

Dislocation‐tuned electrical conductivity in solid electrolytes (9YSZ): A micro‐mechanical approach

Muhammad,

Valderrama,

Yue

et al. 2023

J Am Ceram Soc.

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Tailoring the electrical conductivity of functional ceramics by introducing dislocations is a comparatively recent research focus, and its merits were demonstrated through mechanical means. Especially bulk deformation at high temperatures is suggested to be a promising method to introduce a high dislocation density. So far, however, controlling dislocation generation and their annihilation remains difficult. Although deforming ceramics generate dislocations on multiple length scales, dislocation annihilation at the same time appears to be the bottleneck to use the full potential of dislocations‐tailoring the electrical conductivity. Here, we demonstrate the control over these aspects using a micromechanical approach on yttria‐stabilized zirconia ‐ YSZ. Targeted indentation well below the dislocation annihilation temperature resulted in extremely dense dislocation networks, visualized by chemical etching and electron channeling contrast imaging. Microcontact‐impedance measurements helped evaluate the electrical response of operating individual slip systems. A significant conductivity enhancement is revealed in dislocation‐rich regions compared to pristine ones in fully stabilized YSZ. This enhancement is mainly attributed to oxygen ionic conductivity. Thus, the possibility of increasing the conductivity is illustrated and provides a prospect to transfer the merits of dislocation‐tuned electrical conductivity to solid oxygen electrolytes.

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Dislocation-enhanced electrical conductivity in rutile TiO2 accessed by room-temperature nanoindentation

Cited by 16 publications

References 39 publications

Dislocation-Mediated Oxygen–Ionic Conductivity in Yttria-Stabilized Zirconia

Dislocation-Mediated Oxygen–Ionic Conductivity in Yttria-Stabilized Zirconia

Effect of Cathode Physical Properties on the Preparation of Fe3Si0.7Al0.3 Intermetallic Compounds by Molten Salt Electrode Deoxidation

Dislocation‐tuned electrical conductivity in solid electrolytes (9YSZ): A micro‐mechanical approach

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