Valence-selective local atomic structures in inorganic materials by X-ray fluorescence holography

Hosokawa, Shinya; Happo, Naohisa; Matsushita, Tomohiro; Stellhorn, Jens Rüdiger; Kawasaki, Koji; Hayashi, Kouichi

doi:10.7567/1347-4065/ab5258

Cited by 6 publications

(2 citation statements)

References 27 publications

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“…For the crystal structure analysis, we use white neutron holography, − a kind of atomic resolution holography that can directly reveal a three-dimensional local structure around a dopant without any structure model. The white neutron holography exhibits higher sensitivity to light elements, such as hydrogen, B, and oxygen, compared with X-ray fluorescence holography − and photoelectron holography. − Thanks to the white neutron holography, we successfully revealed that the B-doping site in the Mg 2 Si SCs is the Mg site . Similarly, we determine the B-doping site in the Mg 2 Sn SCs using the white neutron holography.…”

Section: Introductionmentioning

confidence: 91%

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals

Saito

Hayashi

Huang

et al. 2021

ACS Appl. Energy Mater.

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The development of thermoelectric (TE) materials, which can directly convert waste heat into electricity, is vital to reduce the use of fossil fuels. Mg 2 Sn and Mg 2 Si are promising TE materials because of their superior TE performance. In this study, for future improvement of the TE performance, point defect engineering was applied to the Mg 2 Sn and Mg 2 Si single crystals (SCs) via boron (B) doping. Their crystal structures were analyzed via white neutron holography and SC X-ray diffraction. Moreover, nanostructures and TE properties of the B-doped Mg 2 Sn and Mg 2 Si SCs were investigated. The B-doping increased the chemical pressure on the Mg 2 Sn and Mg 2 Si SCs, leading to inducing vacancy defects as a point defect. No apparent change was observed in electronic transport, but thermal transport was significantly prevented. This study demonstrates that the vacancy defects can be controlled by the chemical pressure and can aid in achieving high TE performance for the Mg 2 Sn and Mg 2 Si SCs. KEYWORDS: Mg 2 Sn and Mg 2 Si single crystals, boron-doping, chemical pressure, point defects, thermoelectric properties

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Section: Introductionmentioning

confidence: 91%

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals

Saito

Hayashi

Huang

et al. 2021

ACS Appl. Energy Mater.

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“…Several valence-selective XFH experiments have already been reported for inorganic crystals: a direct-imaging experiment using the same 2D hybrid pixel detector on magnetite (Fe 3 O 4 ) (Ang et al, 2018) and conventional XFH experiments using 0D detectors (avalanche photodiode or SDD) on yttrium oxide thin films (YO/Y 2 O 3 ) and YbInCu 4 (Stellhorn et al, 2017;Hosokawa et al, 2019. In the experiments on Fe 3 O 4 , the difference in the Kossel line features between the high-and low-energy hologram patterns clearly show the valence selectivity (Ang et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Development of serial X-ray fluorescence holography for radiation-sensitive protein crystals

Ang¹,

Umena²,

Sato‐Tomita³

et al. 2023

J Synchrotron Radiat

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X-ray fluorescence holography (XFH) is a powerful atomic resolution technique capable of directly imaging the local atomic structure around atoms of a target element within a material. Although it is theoretically possible to use XFH to study the local structures of metal clusters in large protein crystals, the experiment has proven difficult to perform, especially on radiation-sensitive proteins. Here, the development of serial X-ray fluorescence holography to allow the direct recording of hologram patterns before the onset of radiation damage is reported. By combining a 2D hybrid detector and the serial data collection used in serial protein crystallography, the X-ray fluorescence hologram can be directly recorded in a fraction of the measurement time needed for conventional XFH measurements. This approach was demonstrated by obtaining the Mn Kα hologram pattern from the protein crystal Photosystem II without any X-ray-induced reduction of the Mn clusters. Furthermore, a method to interpret the fluorescence patterns as real-space projections of the atoms surrounding the Mn emitters has been developed, where the surrounding atoms produce large dark dips along the emitter–scatterer bond directions. This new technique paves the way for future experiments on protein crystals that aim to clarify the local atomic structures of their functional metal clusters, and for other related XFH experiments such as valence-selective XFH or time-resolved XFH.

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A cryostat designed for x-ray fluorescence holography experiments down to 4 K

Hayashi

Happo

Hosokawa

2021

Review of Scientific Instruments

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A cryostat was designed for x-ray fluorescence holography (XFH) experiments at low temperatures down to 4 K, where many functional materials show characteristic transitions, such as high-temperature superconducting, magnetic, dielectric, and valence transitions. For XFH measurements, changes in two angles of samples with respect to the incident synchrotron x-ray beam, i.e., incident angle θ and azimuthal angle ϕ, are necessary. A low-temperature specialized small piezoelectric motor is installed at the cryostat head for ϕ, and the cryostat itself is rotated by a stepping motor for θ. The heat from the piezoelectric motor for ϕ and the cryostat power determining the total cryostat mass were optimized for the limited working spaces and beamtimes of synchrotron experiments. Some examples of the XFH results at low temperatures, such as a Pb crystal and an YbInCu4 valence transition material, are presented to show the feasibility of this low-temperature equipment.

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Valence-selective local atomic structures in inorganic materials by X-ray fluorescence holography

Cited by 6 publications

References 27 publications

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals

Development of serial X-ray fluorescence holography for radiation-sensitive protein crystals

A cryostat designed for x-ray fluorescence holography experiments down to 4 K

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Valence-selective local atomic structures in inorganic materials by X-ray fluorescence holography

Cited by 6 publications

References 27 publications

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg2Sn and Mg2Si Single Crystals

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg2Sn and Mg2Si Single Crystals

Development of serial X-ray fluorescence holography for radiation-sensitive protein crystals

A cryostat designed for x-ray fluorescence holography experiments down to 4 K

Contact Info

Product

Resources

About

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg₂Sn and Mg₂Si Single Crystals