scholarly journals Crystal-Field Mediated Electronic Transitions of EuS up to 35 GPa

2021 ◽  
Author(s):  
Virginia Monteseguro ◽  
Jose Antonio Barreda-Argüeso ◽  
Javier Ruiz-Fuertes ◽  
Angelika Rosa ◽  
Holger L. Meyerheim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Crystal Field ◽  
Local Structure ◽  
Electronic Transitions ◽  
Metallic State ◽  
X Ray ◽  
Half Metal ◽  
Consistent Model ◽  
X Ray Absorption ◽  
Pressure Evolution

Abstract An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu2+ in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the 4f75d0 → 4f65d1 electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state.

scholarly journals Interplay between local structure, vibrational and electronic properties on CuO under pressure

2020 ◽  
Vol 22 (42) ◽  
pp. 24299-24309
Author(s):  
Vera Cuartero ◽  
Virginia Monteseguro ◽  
Alberto Otero-de-la-Roza ◽  
Mourad El Idrissi ◽  
Olivier Mathon ◽  
...  
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Ab Initio ◽  
Electronic Properties ◽  
Absorption Spectroscopy ◽  
Local Structure ◽  
X Ray ◽  
X Ray Absorption

X-ray absorption spectroscopy and ab initio calculations unveil the correlation between local, vibrational and electronic structure of CuO under high pressure.

Electronic state analysis of Li2RuO3 positive electrode for lithium ion secondary battery

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040024
Author(s):  
Masatsugu Oishi ◽  
Ryoshi Imura ◽  
Tomoyuki Ueki ◽  
Keiji Shimoda ◽  
Hirona Yamagishi ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Local Structure ◽  
Lithium Ion ◽  
Oxide Material ◽  
X Ray ◽  
Secondary Battery ◽  
Li Ion ◽  
X Ray Absorption

An investigation was made on the electronic structure of 4d transition metal layered oxide material of Li2RuO3 using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The intensity of O [Formula: see text] pre-edge peak increased for Li ion extracted samples, suggesting increased ligand holes. The Ru 3d XPS spectrum suggested the variation of local structure around Ru ions by extraction of Li ions. We conclude that the delithiation from Li2RuO3 is charge compensated by O anions, and that the creation of the ligand holes reorganizes electronic structures composed of highly hybridized Ru 4d and O 2p orbitals.

Enhanced insulating behavior in the Ir-vacant Sr2Ir1–x O4 system dominated by the local structure distortion

2018 ◽  
Vol 25 (4) ◽  
pp. 1123-1128 ◽  
Author(s):  
Jie Cheng ◽  
Peng Dong ◽  
Bin Li ◽  
Shengli Liu ◽  
Xiangfu Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
High Temperature ◽  
Atomic Structure ◽  
Local Structure ◽  
Bond Angle ◽  
Theoretical Calculations ◽  
Unconventional Superconductor ◽  
Microscopic Mechanism ◽  
X Ray ◽  
X Ray Absorption

Sr2IrO4, known as the J eff = 1/2 Mott insulator, was predicted to be an unconventional superconductor upon doping since it highly resembles the high-temperature cuprates. However, recent work pointed out an enhanced insulating behavior in the Ir-vacant Sr2Ir1–x O4 system. In this contribution, to investigate the microscopic mechanism of its enhanced insulating behavior, X-ray absorption spectroscopy was applied to study the electronic structure and local structure distortion of Sr2Ir1–x O4. Due to the presence of Ir5+ ions, the preconceived holes are barely doped in the Ir-vacant system. Nevertheless, Ir vacancies finely modulate the local atomic structure, i.e. the topology of IrO6 octahedra and the in-plane Ir—O1—Ir bond angle. Combined with theoretical calculations, it is demonstrated that both the more distorted IrO6 octahedra and decreased Ir—O1—Ir angle contribute to the increment of the band gap, and then result in the enhanced insulating state for Sr2Ir1–x O4.

Electronic Structure and X-ray Absorption Spectra of Rutile TiO2 Using First-Principles Calculations

2014 ◽  
Vol 52 (12) ◽  
pp. 1025-1029
Author(s):  
Min-Wook Oh ◽  
Tae-Gu Kang ◽  
Byungki Ryu ◽  
Ji Eun Lee ◽  
Sung-Jae Joo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectra ◽  
First Principles ◽  
First Principles Calculations ◽  
Rutile Tio2 ◽  
X Ray ◽  
X Ray Absorption

Application of In Situ X-ray Absorption Spectroscopy to Study Dilute Chromium Ions in a Molten Chloride Salt

2019 ◽  
Author(s):  
Jisue Moon ◽  
Carter Abney ◽  
Dmitriy Dolzhnikov ◽  
James M. Kurley ◽  
Kevin A. Beyer ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Structure ◽  
Chloride Salt ◽  
X Ray ◽  
Molten Chloride ◽  
Stable Species ◽  
Higher Temperature ◽  
Cr Concentration ◽  
X Ray Absorption

The local structure of dilute CrCl<sub>3</sub> in a molten MgCl<sub>2</sub>:KCl salt was investigated by <i>in situ</i> x-ray absorption spectroscopy (XAS) at temperatures from room temperature to 800<sup>o</sup>C. This constitutes the first experiment where dilute Cr speciation is explored in a molten chloride salt, ostensibly due to the compounding challenges arising from a low Cr concentration in a matrix of heavy absorbers at extreme temperatures. CrCl<sub>3</sub> was confirmed to be the stable species between 200 and 500<sup>o</sup>C, while mobility of metal ions at higher temperature (>700<sup>o</sup>C) prevented confirmation of the local structure.

scholarly journals Local Structure and Dynamics of Functional Materials Studied by X-ray Absorption Fine Structure

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1315
Author(s):  
Takafumi Miyanaga
Keyword(s):  
Fine Structure ◽  
Local Structure ◽  
Chemical Reactivity ◽  
Functional Materials ◽  
X Ray ◽  
Structure And Dynamics ◽  
Absorption Fine ◽  
Structure Phase Transition ◽  
Local Electronic Structure ◽  
X Ray Absorption

X-ray absorption fine structure (XAFS) is a powerful technique used to analyze a local electronic structure, local atomic structure, and structural dynamics. In this review, I present examples of XAFS that apply to the local structure and dynamics of functional materials: (1) structure phase transition in perovskite PbTiO3 and magnetic FeRhPd alloys; (2) nano-scaled fluctuations related to their magnetic properties in Ni–Mn alloys and Fe/Cr thin films; and (3) the Debye–Waller factors related to the chemical reactivity for catalysis in polyanions and ligand exchange reaction. This study shows that the local structure and dynamics are related to the characteristic function of the materials.

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