Epr Spectroscopy on Zn-Substituted YBa2Cu3O7

1987 ◽  
Vol 99 ◽  
Author(s):  
A. M. Ponte Goncalves ◽  
Chan-Soo Jee ◽  
D. Nichols ◽  
J. E. Crow ◽  
G. H. Myer ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Transition Temperature ◽  
Epr Spectroscopy ◽  
Superconducting Transition Temperature ◽  
Superconducting Phase ◽  
Superconducting Transition ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
Cu Ions ◽  
Bulk Response

ABSTRACTThe temperature and concentration dependence of the electron paramagnetic resonance spectra of YBa2(Cu1−xZnx)3O7 has been measured for 0≤x≤0.16. Zn substituted on the Cu-site cause a rapid nearly linear depression of the superconducting transition temperature Tc with Tc going to zero in the vicinity of x=0.10. Only weak EPR spectra due to ≤1% of the Cu-ions are seen in the superconducting phase of YBa2Cu3O7. These spectra are most likely attributed to Cu-ions in the vicinity of grain boundaries and do not represent a bulk response. However, a strong asymmetric resonance is observed in the Zn-substituted samples with x>0.1. The EPR results obtained for YBa2(Cu1−xZnx)3O7 are discussed in terms of a possible localization of d-electrons.

scholarly journals Paramagnetic Resonance as a Probe of the Spin Gap in Normal State of Superconductor

2011 ◽  
Vol 2011 ◽  
pp. 1-3
Author(s):  
Frank J. Owens
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Transition Temperature ◽  
Normal State ◽  
Oxide Superconductors ◽  
Superconducting Transition ◽  
Paramagnetic Resonance ◽  
Spin Gap ◽  
Order Of Magnitude ◽  
Copper Oxide Superconductors ◽  
Electron Paramagnetic

It is shown that electron paramagnetic resonance (EPR) can be used to observe the spin gap in copper oxide superconductors. The electron paramagnetic resonance spectra of the Cu2+ ion in underdoped show a pronounced decrease in intensity in the normal state as the temperature is lowered to 133 K, the superconducting transition temperature of the material. The decrease is attributed to a pairing of the Cu2+   spins to form a spin gap. A spin gap of 0.0533 eV is estimated from the data which is in order of magnitude agreement with values obtained from NMR measurements.

scholarly journals Enhancing Superconductivity of the Nonmagnetic Quasiskutterudites by Atomic Disorder

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5830
Author(s):  
Andrzej Ślebarski ◽  
Maciej M. Maśka
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
High Temperature Superconductors ◽  
Superconducting Phase ◽  
Length Scale ◽  
Superconducting Transition ◽  
Atomic Disorder ◽  
Strong Inhomogeneity ◽  
Related Compounds

We investigated the effect of enhancement of superconducting transition temperature Tc by nonmagnetic atom disorder in the series of filled skutterudite-related compounds (La3M4Sn13, Ca3Rh4Sn13, Y5Rh6Sn18, Lu5Rh6Sn18; M= Co, Ru, Rh), where the atomic disorder is generated by various defects or doping. We have shown that the disorder on the coherence length scale ξ in these nonmagnetic quasiskutterudite superconductors additionally generates a non-homogeneous, high-temperature superconducting phase with Tc⋆>Tc (dilute disorder scenario), while the strong fluctuations of stoichiometry due to increasing doping can rapidly increase the superconducting transition temperature of the sample even to the value of Tc⋆∼2Tc (dense disorder leading to strong inhomogeneity). This phenomenon seems to be characteristic of high-temperature superconductors and superconducting heavy fermions, and recently have received renewed attention. We experimentally documented the stronger lattice stiffening of the inhomogeneous superconducting phase Tc⋆ in respect to the bulk Tc one and proposed a model that explains the Tc⋆>Tc behavior in the series of nonmagnetic skutterudite-related compounds.

Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy

2015 ◽  
Vol 98 (4) ◽  
pp. 866-870 ◽  
Author(s):  
Violetta Kozik ◽  
Krystyna Jarzembek ◽  
Agnieszka Jędrzejowska ◽  
Andrzej Bąk ◽  
Justyna Polak ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Antioxidant Properties ◽  
Free Radical Scavenger ◽  
Pomegranate Juice ◽  
Radical Scavenger ◽  
Paramagnetic Resonance ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic

Abstract Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r) = 0.90 and determination coefficient (r2) = 0.81 (P <0.05).

scholarly journals Chain initiation

2019 ◽  
Vol 89 (2) ◽  
pp. 179-186
Author(s):  
V. V. Ptushenko
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Epr Spectroscopy ◽  
Paramagnetic Resonance ◽  
Chain Initiation ◽  
Radio Spectroscopy ◽  
Scientific Instrumentation ◽  
History Of ◽  
Scientists And Engineers ◽  
Electron Paramagnetic

This article describes the formation of the chemical electron paramagnetic resonance (EPR) spectroscopy institute established by Academician Vladislav V. Voevodsky (1917–1967) along with the history of the development of the instrumentation basis for this field of science in the Union of Soviet Socialist Republics (USSR). The design of the first EPR spectrometers for the chemical radio spectroscopy initiated the emergence of a new scientific instrumentation field in this country. Based on recollections shared by scientists and engineers and an examination of archive materials, the author reconstructs relevant events and identifies major participants in this process.

A Study of V3+/4+ Levels in Semi-insulating 6H-SiC using Optical Admittance and Electron Paramagnetic Resonance Spectroscopies

2006 ◽  
Vol 911 ◽  
Author(s):  
Wonwoo Lee ◽  
Mary E Zvanut
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Charge State ◽  
Conduction Band ◽  
Epr Spectroscopy ◽  
Admittance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Characteristic Spectrum ◽  
Epr Measurements ◽  
The Individual ◽  
Electron Paramagnetic

AbstractThe purpose of this study is to identify the vanadium acceptor levels in semi-insulating (SI) 6H-SiC using optical admittance spectroscopy (OAS) and electron paramagnetic resonance (EPR) spectroscopy. OAS conductance peaks near at 0.67 ± 0.02 eV and 0.70 ± 0.02 eV are identified as V3+/4+ levels at the quasi-cubic sites. An OAS peak at 0.87 eV is assigned to the same transition at the hexagonal site. EPR measurements before illumination revealed the characteristic spectrum of V3+. The presence of the V3+ signal supports the identification of the OAS peaks as transitions from the V3+/4+ level to the conduction band. Photo-induced EPR measurements reveal a change in the intensity of V3+ and V4+ at 0.8 ± 0.1 eV, where the amplitude of the V3+ charge state decreases and that of V4+ increases by approximately equal amounts. Although the individual sites are not resolved in the photo-induced EPR data, the 0.8 eV feature strongly supports the assignment of the three OAS peaks as acceptor levels.

Ultra-broadband EPR spectroscopy in field and frequency domains

2018 ◽  
Vol 20 (22) ◽  
pp. 15528-15534 ◽  
Author(s):  
P. Neugebauer ◽  
D. Bloos ◽  
R. Marx ◽  
P. Lutz ◽  
M. Kern ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Properties ◽  
Epr Spectroscopy ◽  
Paramagnetic Resonance ◽  
Powerful Technique ◽  
Electronic And Magnetic Properties ◽  
Wide Range ◽  
Frequency Domains ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) is a powerful technique to investigate the electronic and magnetic properties of a wide range of materials.

Sign in / Sign up

Export Citation Format

Share Document