Superconducting Sr<sub>2</sub>RuO<sub>4</sub> Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden–Popper Intergrowth

Kim, Jinkwon; Mun, Je‐Ho; Garciá, Carla M. Palomares; Kim, Bongju; Perry, Robin; Jo, Young‐Heon; Im, Hyunsik; Lee, Han Gyeol; Ko, Eun Kyo; Chang, Seo Hyoung; Chung, Suk Bum; Kim, Miyoung; Robinson, Jason W. A.; Yonezawa, Suguru; Maeno, Y.; Wang, Lingfei; Noh, Tae Won

doi:10.1021/acs.nanolett.0c04963

Cited by 20 publications

(9 citation statements)

References 45 publications

(83 reference statements)

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“…However, this does not change the surface electric and crystal structures, as well the high conductivity of SRO. (43) The surface electronic structures of SRO single crystal are investigated by X-ray photoelectron spectroscopy (XPS). The survey spectrum demonstrates the existence of Sr, Ru, and O elements besides the common C contamination (Fig.…”

Section: Resultsmentioning

confidence: 99%

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Zhang

Arpino

Yang

et al. 2022

Preprint

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Despite the fruitful achievements in the development of hydrogen production catalysts with record-breaking performances, there is still a lack of durable catalysts that could work under large current densities (> 1000 mA cm− 2). In the context of this need, we investigated the catalytic behaviors of Sr2RuO4 (SRO) bulk single crystals with well-defined surface crystal structures, which is a benchmark material to explore exotic metallic states and electronic structures. This single crystal has demonstrated remarkable activities under the current density of 1000 mA cm− 2, which require overpotentials of 182 and 278 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively, after ohmic correction. These values slightly increased to 272 and 354 mV even without iR correction, exhibiting high potential for industrial-scale hydrogen production. The high performance is also evidenced by the 56 days of continuous testing at a high current density of above 1000 mA cm− 2 and then under operating temperatures of 70 ℃ for alkaline electrolysis. The in-situ formation of ferromagnetic Ru clusters at the crystal surface is critical for the outstanding catalytic activity, endowing the single-crystal catalyst with low charge transfer resistance and high wettability for rapid gas bubble removal. Density functional theory calculations indicate that SRO gains electrons from the Ru clusters, thus leading to the thermodynamically favorable hydrogen desorption for the rapidly modified catalysts. More generally, our experiment exemplifies the potential of designing novel HER catalysts that work under industrial-scale current density.

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Section: Resultsmentioning

confidence: 99%

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Zhang

Arpino

Yang

et al. 2022

Preprint

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“…24 In other cases, layers of mixed n can be harnessed to help alleviate substrate effects such as step edges. 25 Thus, in regions of high heterogeneity, mapping the junctions between various n-phases can provide insight to how local structural phases are formed and arranged within the material.…”

Section: Discussionmentioning

confidence: 99%

Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

Fleck¹,

Barone²,

Nair³

et al. 2022

Preprint

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The Ruddlesden-Popper (A n+1 B n O 3n+1 ) compounds are a highly tunable class of materials whose functional properties can be dramatically impacted by their structural phase n. The negligible energetic differences associated with forming a sample with a single value of n versus a mixture of n makes the growth of these materials difficult to control and can lead to local atomic-scale structural variation arising from small stoichiometric deviations. In this work, we present a Python analysis platform to detect, measure, and quantify the presence of different n-phases based on atomic-resolution scanning transmission electron microscopy (STEM) images in a statistically rigorous manner. We employ phase analysis on the 002 Bragg peak to identify horizontal Ruddlesden-Popper faults which appear as regions of high positive compressive strain within the lattice image, allowing us to quantify the local structure. Our semi-automated technique offers statistical advantages by considering effects of finite projection thickness, limited fields of view, and precise sampling rates. This method retains the real-space distribution of layer variations allowing for a spatial mapping of local n-phases, enabling both quantification of intergrowth occurrence as well as qualitative description of their distribution, opening the door to new insights and levels of control over a range of layered materials.

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“…Such extended defects greatly disrupt the transport behavior of A 2 B O 4 thin films, such as resistivity, [ 18 ] magnetoelectric properties, [ 19 ] and superconductivity. [ 20–22 ] Hence, OPBs must be suppressed to fabricate high‐quality electronic devices based on A 2 B O 4 thin films.…”

Section: Introductionmentioning

confidence: 99%

“…This kind of OPB is described as a steric OPB. [ 18,22 ] As the vicinal surface and accompanying step edges always exist at substrate surfaces, steric OPBs are prevalent when A 2 B O 4 thin films are grown on A ″ B ″O 3 substrates.…”

Section: Introductionmentioning

confidence: 99%

Defect Engineering in A₂BO₄ Thin Films via Surface‐Reconstructed LaSrAlO₄ Substrates

Kim

Mun

et al. 2022

Small Methods

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Ruddlesden–Popper oxides (A2BO4) have attracted significant attention regarding their potential application in novel electronic and energy devices. However, practical uses of A2BO4 thin films have been limited by extended defects such as out‐of‐phase boundaries (OPBs). OPBs disrupt the layered structure of A2BO4, which restricts functionality. OPBs are ubiquitous in A2BO4 thin films but inhomogeneous interfaces make them difficult to suppress. Here, OPBs in A2BO4 thin films are suppressed using a novel method to control the substrate surface termination. To demonstrate the technique, epitaxial thin films of cuprate superconductor La2‐xSrxCuO4 (x = 0.15) are grown on surface‐reconstructed LaSrAlO4 substrates, which are terminated with self‐limited perovskite double layers. To date, La2‐xSrxCuO4 thin films are grown on LaSrAlO4 substrates with mixed‐termination and exhibit multiple interfacial structures resulting in many OPBs. In contrast, La2‐xSrxCuO4 thin films grown on surface‐reconstructed LaSrAlO4 substrates energetically favor only one interfacial structure, thus inhibiting OPB formation. OPB‐suppressed La2‐xSrxCuO4 thin films exhibit significantly enhanced superconducting properties compared with OPB‐containing La2‐xSrxCuO4 thin films. Defect engineering in A2BO4 thin films will allow for the elimination of various types of defects in other complex oxides and facilitate next‐generation quantum device applications.

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Superconducting Sr₂RuO₄ Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden–Popper Intergrowth

Cited by 20 publications

References 45 publications

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

Defect Engineering in A₂BO₄ Thin Films via Surface‐Reconstructed LaSrAlO₄ Substrates

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Superconducting Sr2RuO4 Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden–Popper Intergrowth

Cited by 20 publications

References 45 publications

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

Defect Engineering in A2BO4 Thin Films via Surface‐Reconstructed LaSrAlO4 Substrates

Contact Info

Product

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Superconducting Sr₂RuO₄ Thin Films without Out-of-Phase Boundaries by Higher-Order Ruddlesden–Popper Intergrowth

Defect Engineering in A₂BO₄ Thin Films via Surface‐Reconstructed LaSrAlO₄ Substrates