scholarly journals The Impact of Hydrogenation on Structural and Superconducting Properties of FeTe0.65Se0.35 Single Crystals

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7900
Author(s):  
Stanislav I. Bondarenko ◽  
Anatolij I. Prokhvatilov ◽  
Roman Puźniak ◽  
Jarosław Piętosa ◽  
Andrey A. Prokhorov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Structural Changes ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Paramagnetic Resonance ◽  
The Impact ◽  
Electron Paramagnetic ◽  
Diffusion Of Hydrogen

Properties of FeTe0.65Se0.35 single crystals, with the onset of critical temperature (Tconset) at 15.5 K, were modified via hydrogenation performed for 10–90 h, at temperatures ranging from 20 to 250 °C. It was found that the tetragonal matrix became unstable and crystal symmetry lowered for the samples hydrogenated already at 200 °C. However, matrix symmetry was not changed and the crystal was not destroyed after hydrogenation at 250 °C. Bulk Tcbulk, determined at the middle of the superconducting transition, which is equal to 12–13 K for the as grown FeTe0.65Se0.35, rose by more than 1 K after hydrogenation. The critical current density studied in magnetic field up to 70 kOe increased 4–30 times as a consequence of hydrogenation at 200 °C for 10 h. Electron paramagnetic resonance measurements also showed higher values of Tcbulk for hydrogenated crystals. Thermal diffusion of hydrogen into the crystals causes significant structural changes, leads to degeneration of crystal quality, and significantly alters superconducting properties. After hydrogenation, a strong correlation was noticed between the structural changes and changes in the parameters characterizing the superconducting state.

scholarly journals The Effect of Hydrogenation on Structure and Superconducting Properties of FeTe0.65Se0.35 Single Crystals

2021 ◽  
Author(s):  
S. I. Bondarenko ◽  
A. I. Prokhvatilov ◽  
Roman Puzniak ◽  
Jaroslaw Pietosa ◽  
A. A. Prokhorov ◽  
...  
Keyword(s):  
Single Crystals ◽  
Structural Changes ◽  
Superconducting Properties ◽  
Field Range ◽  
Paramagnetic Resonance ◽  
Magnetic Field Range ◽  
Change Matrix ◽  
Electron Paramagnetic ◽  
Diffusion Of Hydrogen ◽  
Critical Temperature Tc

Abstract Single crystals of FeTe0.65Se0.35, with the onset of critical temperature (Tc) at 14 K, were hydrogenated for 10–90 hours at various temperatures, ranging from 20 to 250 oC. It is shown that tetragonal matrix becomes unstable and crystal symmetry is reduced for the crystals hydrogenated already at 200 oC despite that molecular impurities do not change matrix symmetry, unless the material is not destroyed under hydrogenation at 250 oC. Bulk Tc, takenat the middle of the transition, equal to about 12–13 K for the as-grown FeTe0.65Se0.35, increases by 1–2 K. The critical current density determined in magnetic field range of 0–70 kOe increases 4–30 times as a result of hydrogenation at 200 oC for 10 h. Electron paramagnetic resonance studies confirmed higher value of the bulk Tc for hydrogenated crystals. Thermal diffusion of hydrogen leads to substantial structural changes, causes degeneration of crystal quality, and significantly affects superconducting properties. A strong correlation was observed between the structural changes and changes in the parameters of the superconducting state for the hydrogenated crystals.

The Electron Paramagnetic Resonance Spectrum of γ-Irradiated Dimethyl Malonic Acid

2004 ◽  
Vol 59 (1-2) ◽  
pp. 103-104 ◽  
Author(s):  
Biray Aşik ◽  
Mehmet Birey
Keyword(s):  
Magnetic Field ◽  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectrum ◽  
Single Crystals ◽  
Malonic Acid ◽  
Hyperfine Coupling ◽  
Resonance Spectrum ◽  
Coupling Constants ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The electron paramagnetic resonance of γ -Irradiated single crystals of dimethyl malonic acid [(CH3)2C(COOH)2] has been studied for different orientations of the crystal in a magnetic field. The radicals produced by gamma irradiation have been investigated between 123 and 300 K. The spectra were found to be temperature independent, and radiation damage centres were attributed to [(CH3)2C(COOH)2]+ radicals. The g factor and hyperfine coupling constants were found to be almost isotropic with average values g = 2.0036, a(COOH)2 = 0.5 mT, a(CH3)2 = 2.1 mT, respectively, and spin density ρ = 91% of the [(CH3)2C(COOH)2]+ radical.

Catalytic and Electron Paramagnetic Resonance Spectroscopic Characterization of γ-Al2O3 in a Non-Thermal Plasma

2005 ◽  
Vol 8 (1) ◽  
Author(s):  
Ulf Roland ◽  
Frank Holzer ◽  
Andreas Pöppl ◽  
Frank-Dieter Kopinke
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Thermal Plasma ◽  
Pore Volume ◽  
Structural Changes ◽  
Peroxide Radical ◽  
Paramagnetic Resonance ◽  
Non Thermal Plasma ◽  
The Impact ◽  
Electron Paramagnetic ◽  
Inner Pore

AbstractIn order to evaluate the potential of the combination of non-thermal plasma (NTP) and in situ heterogeous catalysis (plasma catalysis) for the improvement of efficiency and selectivity towards total oxidation of organic pollutants, the impact of plasma processes inside the inner pore volume of porous materials was investigated by means of catalytic reactions and spectroscopy. Besides studying the conversion of organic model substances, electron paramagnetic resonance (EPR) spectroscopy was applied to detect both the formation of radical species by the NTP and the initiation of structural changes to the catalyst. The presence of short-lived oxidizing species and plasma effects in the inner pore volume of porous catalysts (alumina in this case) could be clearly shown by detecting a significant influence on the oxidation process and the formation of a paramagnetic site which can be correlated to an aluminum peroxide radical: Al-O-O. The relatively stable paramagnetic center (lifetime > 14 days) was formed by the NTP independently of the gas atmosphere, namely its oxygen content. The signal was not significantly affected by the application of reducing agents to the sample.

EPR of VO2+ in ZnTiF6 · 6H2O

1996 ◽  
Vol 51 (4) ◽  
pp. 245-248
Author(s):  
Geetha Jayaram ◽  
V. G. Krishnan
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Tutton Salts ◽  
Bonding Parameters ◽  
Superhyperfine Structure ◽  
Vanadyl Ion ◽  
Electron Paramagnetic

Abstract Electron Paramagnetic Resonance (EPR) studies have been carried out on the vanadyl (VO2) ion doped in single crystals of ZnTiF6 • 6H2O. The spectra indicate the presence of one set of eight lines characteristic of only one occupation site. The V-O bond orientation is along one of the three Zn-H2O bond directions in the trigonally distorted [Zn(H2O)6] octahedra. This behaviour is unlike that reported for vanadyl ion substituting for the M(H2O)6 sites in the Tutton salts, alums and AlCl3 • 6H2O. The Spin-Hamiltonian and bonding parameters for the [VO(H2O)5] complex have been evaluated. The hyperfine linewidths are 0.8 mT at 300 K and 77 K. No proton superhyperfine structure was observed at both these temperatures.

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