Magnetic Behavior and Chemical Shift of Amorphous Cr2O3

The chemical shift in cristalline and amorphous Cr2O3 was determined from the X-ray absorption Cr K edge spectra. The measurements of the temperature dependence of the reciprocal susceptibility between 100 and 1200 K show an antiferromagnetic behavior for the cristalline sample, with the Neel temperature at 318 K, and a linear dependence (Curie-Weiss law) with θp<0, for the amorphous oxide.

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Tuning the Néel temperature in an antiferromagnet: the case of NixCo1−xO microstructures

Scientific Reports ◽

10.1038/s41598-019-49642-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Anna Mandziak ◽

Guiomar D. Soria ◽

José Emilio Prieto ◽

Pilar Prieto ◽

Cecilia Granados-Miralles ◽

...

Keyword(s):

Molecular Beam ◽

Linear Dichroism ◽

Antiferromagnetic Order ◽

Neel Temperature ◽

Néel Temperature ◽

X Ray ◽

Magnetic Linear Dichroism ◽

Low Energy Electron ◽

X Ray Absorption ◽

Antiferromagnetic Domains

Abstract We show that it is possible to tune the Néel temperature of nickel(II)-cobalt(II) oxide films by changing the Ni to Co ratio. We grow single crystalline micrometric triangular islands with tens of nanometers thickness on a Ru(0001) substrate using high temperature oxygen-assisted molecular beam epitaxy. Composition is controlled by adjusting the deposition rates of Co and Ni. The morphology, shape, crystal structure and composition are determined by low-energy electron microscopy and diffraction, and synchrotron-based x-ray absorption spectromicroscopy. The antiferromagnetic order is observed by x-ray magnetic linear dichroism. Antiferromagnetic domains up to micrometer width are observed.

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Ferromagnetism and Luminescence of Diluted Magnetic Semiconductors GaGdN and AlGdN

MRS Proceedings ◽

10.1557/proc-1111-d03-01 ◽

2008 ◽

Vol 1111 ◽

Author(s):

Shuichi Emura ◽

Masahiro Takahashi ◽

Hiroyuki Tambo ◽

Akira Suzuki ◽

Tetsuya Nakamura ◽

...

Keyword(s):

Temperature Dependence ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Magnetic Circular Dichroism ◽

Peak Position ◽

Magnetic Characteristics ◽

Sharp Line ◽

X Ray ◽

Diluted Magnetic ◽

X Ray Absorption

AbstractThe magnetic characteristics of the dilute magnetic system GaGdN are investigated by mainly soft-X-ray magnetic circular dichroism (MCD) in energy range of 1160 – 1240 eV. The strong MCD signals up to 30 % at 15K are observed. The temperature dependence of its intensity is not on simple Curie-Weiss curve and depicts three-step curve. A step around 40 – 100K suggests a new magnetic phase. The luminescence spectrum of GaGdN at low temperature is divided into three parts consisting of two broad bands around 432 nm and 503 nm and a sharp peak at 652 nm. This sharp line is assigned to the intra-transition of f – f orbital owing to the weak temperature dependence of the intensity and peak position. AlGdN grown by molecular beam epitaxy produces luminescence at 318.5 nm. X-ray absorption fine structure is examined to survey the occupancy of the Gd ion in the grown specimens.

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Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Scientific Reports ◽

10.1038/s41598-021-02261-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Gen-ichiro Yamamoto ◽

Atsushi Kyono ◽

Satoru Okada

Keyword(s):

Temperature Dependence ◽

Three Dimensional ◽

Magnesium Carbonate ◽

Range Order ◽

Edge Structure ◽

Medium Range Order ◽

X Ray ◽

Medium Range ◽

Mineral Trapping ◽

X Ray Absorption

AbstractMineral trapping through the precipitation of carbonate minerals is a potential approach to reduce CO2 accumulation in the atmosphere. The temperature dependence of amorphous magnesium carbonate (AMC), a precursor of crystalline magnesium carbonate hydrates, was investigated using synchrotron X-ray scattering experiments with atomic pair distribution function (PDF) and X-ray absorption fine structure analysis. PDF analysis revealed that there were no substantial structural differences among the AMC samples synthesized at 20, 60, and 80 °C. In addition, the medium-range order of all three AMC samples was very similar to that of hydromagnesite. Stirring in aqueous solution at room temperature caused the AMC sample to hydrate immediately and form a three-dimensional hydrogen-bonding network. Consequently, it crystallized with the long-range structural order of nesquehonite. The Mg K-edge X-ray absorption near-edge structure spectrum of AMC prepared at 20 °C was very similar to that of nesquehonite, implying that the electronic structure and coordination geometry of Mg atoms in AMC synthesized at 20 °C are highly similar to those in nesquehonite. Therefore, the short-range order (coordination environment) around the Mg atoms was slightly modified with temperature, but the medium-range order of AMC remained unchanged between 20 and 80 °C.

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Satellite absorption lines and the temperature dependence of x-ray absorption features in high-temperature plasmas

Physical Review A ◽

10.1103/physreva.43.961 ◽

1991 ◽

Vol 43 (2) ◽

pp. 961-967 ◽

Cited By ~ 12

Author(s):

R. Epstein

Keyword(s):

High Temperature ◽

Temperature Dependence ◽

Absorption Lines ◽

X Ray ◽

X Ray Absorption ◽

Absorption Features

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Preliminary investigation of chlorine speciation in zirconolite glass-ceramics for plutonium residues by analysis of Cl K-edge XANES

MRS Advances ◽

10.1557/adv.2019.460 ◽

2019 ◽

Vol 5 (1-2) ◽

pp. 37-43

Author(s):

Amber R. Mason ◽

Stephanie M. Thornber ◽

Martin C. Stennett ◽

Laura J. Gardner ◽

Dirk Lützenkirchen-Hecht ◽

...

Keyword(s):

Chemical Shift ◽

Absorption Edge ◽

Glass Ceramic ◽

Glass Phase ◽

Preliminary Investigation ◽

Glass Ceramics ◽

Local Environment ◽

Aluminosilicate Glass ◽

X Ray ◽

X Ray Absorption

ABSTRACTA zirconolite glass-ceramic material is a candidate wasteform for immobilisation of chlorine contaminated plutonium residues, in which plutonium and chlorine are partitioned to the zirconolite and aluminosilicate glass phase, respectively. A preliminary investigation of chlorine speciation was undertaken by analysis of Cl K-edge X-ray Absorption Near Edge Spectroscopy (XANES), to understand the incorporation mechanism. Cl was found to be speciated as the Cl- anion within the glass phase, according to the characteristic chemical shift of the X-ray absorption edge. By comparison with Cl K-edge XANES data acquired from reference compounds, the local environment of the Cl- anion is most closely approximated by the mineral marialite, in which Cl is co-ordinate to 4 x Na and/or Ca atoms.

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