Element-selective local structural analysis around 
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-site cations in multiferroic 
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Kawasaki, Koji; Urushihara, Daisuke; Rikuya, Kondo; Yamamoto, Yuta; Ang, Artoni Kevin R.; Asaka, Toru; Happo, Naohisa; Hagihara, Takeshi; Matsushita, Tomohiro; Tajiri, Hiroo; Miyazaki, Hitoshi; Ohara, Koji; Iwata, Makoto; Hayashi, Kouichi

doi:10.1103/physrevb.104.144101

Cited by 8 publications

(3 citation statements)

References 52 publications

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“…However, they were missing in the atomic images in the upper panel. Missing oxygen anions were observed in the reconstruction on lanthanum Lγ holograms of SrTiO 3 doped with La cations, niobium Kα holograms of Pb(Fe 1/2 Nb 1/2 )O 3 , and calcium Kα and barium Lγ holograms of (Ba 0.9 Ca 0.1 )TiO 3 . The missing anions are interpreted with the limited X-ray scattering power of oxygen.…”

Section: Resultsmentioning

confidence: 91%

KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

et al. 2022

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Potassium tantalate (KTaO 3 ) is a highly efficient semiconductor photocatalyst for the overall water-splitting reaction. Doping a semiconductor photocatalyst with foreign metal cations typically increases the apparent quantum yield of the splitting reaction. In this study, we constructed a single-crystalline model of cation-doped photocatalysts, which would be suitable for future investigation with advanced surface-sensitive methods. Centimetersized (001)-oriented KTaO 3 wafers were doped with Sr or La cations in KCl flux. X-ray diffraction (XRD) revealed Sr-and La-containing perovskite-structured layers epitaxially covering bulk KTaO 3 . On the Sr-doped wafer, the surface-layer lattice was expanded by 2% relative to the bulk lattice. X-ray fluorescence holography (XFH) was employed to determine the 3D short-range ordered structure around the K and Sr cations. Holograms obtained with Sr Kα fluorescence confirmed the simultaneous settling of Sr cations in the A and B sites. The placement of the Sr cations in B sites was supported by the TaO 6 breathing vibration observed in Raman scattering. These experimental results suggested that a KTaO 3 −Sr(Sr 1/3 Ta 2/3 )O 3 solid solution is generated by doping. Two La-containing phases, one with lattice contraction by 2% and the other with expansion by 0.4%, were recognized on the La-doped wafer. La Lα fluorescence holograms indicated a complex manner of doping. The obtained atom distribution around La cations was interpreted by the simultaneous La cation occupation at the A-site, B-site, and an interstitial site. Local lattice deformation was quantitatively deduced around the La cations occupying the interstitial site. Element composition determined by X-ray photoelectron spectroscopy revealed the enrichment of doping elements on the wafer surface. Nanometer-scale topography observed by atomic force microscopy suggested that doping concentrations should be optimized to provide flat, crystalline surfaces.

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Section: Resultsmentioning

confidence: 91%

KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

et al. 2022

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“…作为X射线的能量标准广泛应用于先进功能材料研究, 高温等离子体的光学诊断和天体物理研究等领域, 多电荷态离子与原子相互作用的X射线产生截面数据也被用于原子结构探索和物质成分分析等 [14][15][16][17][18] . 因此离子与原子碰撞作为研究X射线手段目前已成为重要的研究课题.…”

Section: 常见原子的特征X射线(k L壳层x射线)unclassified

K-X rays induced by helium-like C ions in thick target atoms of different metals

Mei,

Zhang,

Zhou

et al. 2024

Acta Phys. Sin.

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The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex, particularly in the intermediate energy region, because of the limitation of accelerator and existing theoretical analysis, the systematic research is relatively few, the atomic data are incomplete and the accuracy is not high, and the research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce. Helium-like C ions with 15~55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe, Ni, Nb and Mo thick targets. The HpGe detectors are used to measure the K X ray emission, and the corresponding K X ray emission cross sections are obtained. Due to the different ionization degrees of the shell layers of various target atoms, the branching intensity ratio of Kβ to Kα X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions, while the branching intensity ratio of KX rays emitted by Nb and Mo target atoms does not change significantly. The K X ray emission cross section of target atom is calculated by using the thick target cross section formula, and compared with the results of different theoretical models and proton. The results show that with the increase of the kinetic energy of helium-like C ions, the total emission cross section of the Kβ and Kα X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization, and the total emission cross section of Kβ and Kα X ray emitted from Nb and Mo target atoms are most close to the theoretical values of PWBA model. When the energy of proton is the same as that of single nucleon C ion, the cross section of K X ray produced by proton is about 3 orders of magnitude smaller than that produced by helium-like C ion.

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“…X-ray fluorescence holography (XFH) can extract three-dimensional (3D) atomic images around specific elements emitting fluorescent X-rays and can determine the local atomic arrangements within the short and intermediate range of up to a few nanometers around these emitting atoms. , In particular, XFH is very effective in identifying the location of impurity sites and the local lattice deformation around the impurity atoms. Therefore, XFH has been applied to discover new structures centered around additive atoms. − For example, in lead-free ferroelectric (Ba,Ca)TiO 3 , a large off-center displacement of Ca was estimated by XFH, and the significant role of Ca in ferroelectricity was discussed . Moreover, in a solar cell material As-doped CdTe, we found that a certain amount of As was coupled with Cd vacancies and formed deep impurity levels …”

Section: Introductionmentioning

confidence: 98%

Nanophase Separation in K_1–xCa_xC₈ Revealed by X-ray Fluorescence Holography and Extended X-ray Absorption Fine Structure

Happo,

Kubota,

Yang

et al. 2024

Chem. Mater.

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Even at low Ca concentrations, the binary-element intercalated graphite K 1−x Ca x C 8 exhibits high superconducting transition temperatures T c , closer to that of CaC 6 (11.5 K) than KC 8 (0.169 K). To investigate the behaviors of K and Ca within the graphite matrix, their local structures have been investigated by using X-ray fluorescence holography and extended X-ray absorption fine structure (EXAFS) spectroscopy. The atomic images reconstructed from the K−Kα and Ca−Kβ holograms showed that K 0.7 Ca 0.3 C 8 did not take the solidsolution type random distribution of Ca and K atoms; instead, a nanoscale phase separation of CaC 6 and KC 8 was observed, which was also supported by the EXAFS results. While the lattice constant of K 0.7 Ca 0.3 C 8 was close to that of KC 8 , we found a nanoscale Ca layer dispersed within the sample. The Ca nanolayer was offset from the center between the C sublayers. The superconducting behavior found in K 1−x Ca x C 8 was discussed with two scenarios of percolation of CaC 6 and deformation of graphene based on such a specific inhomogeneous binary element monatomic layers. This study represents an important step for understanding the superconducting properties in a nanoscale phase-separated system.

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Element-selective local structural analysis around B -site cations in multiferroic Pb(Fe1/2Nb1/2

Cited by 8 publications

References 52 publications

KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

K-X rays induced by helium-like C ions in thick target atoms of different metals

Nanophase Separation in K_1–xCa_xC₈ Revealed by X-ray Fluorescence Holography and Extended X-ray Absorption Fine Structure

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Element-selective local structural analysis around B -site cations in multiferroic Pb(Fe1/2Nb1/2

Cited by 8 publications

References 52 publications

KTaO3 Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

KTaO3 Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

K-X rays induced by helium-like C ions in thick target atoms of different metals

Nanophase Separation in K1–xCaxC8 Revealed by X-ray Fluorescence Holography and Extended X-ray Absorption Fine Structure

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KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

KTaO₃ Wafers Doped with Sr or La Cations for Modeling Water-Splitting Photocatalysts: 3D Atom Imaging around Doping Cations

Nanophase Separation in K_1–xCa_xC₈ Revealed by X-ray Fluorescence Holography and Extended X-ray Absorption Fine Structure