Magnetic order and electrical conductivity scaling of the spinel oxideMn0.5Ru0.5Co2O4

2006 ◽  
Vol 74 (21) ◽  
Author(s):  
R. N. Bhowmik ◽  
R. Ranganathan
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Order

scholarly journals Reversible redox switching of magnetic order and electrical conductivity in a 2D manganese benzoquinoid framework

2020 ◽  
Author(s):  
Lujia Liu
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Single Crystal ◽  
Magnetic Order ◽  
Magnetic Measurements ◽  
Fold Increase ◽  
Parent Material ◽  
Formidable Challenge ◽  
Redox Switching ◽  
Magnetic And Electrical Properties

© 2019 The Royal Society of Chemistry. Materials with switchable magnetic and electrical properties may enable future spintronic technologies, and thus hold the potential to revolutionize how information is processed and stored. While reversible switching of magnetic order or electrical conductivity has been independently realized in materials, the ability to simultaneously switch both properties in a single material presents a formidable challenge. Here, we report the 2D manganese benzoquinoid framework (Me4N)2[MnII2(L2-)3] (H2L = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinone), as synthesized via post-synthetic counterion exchange. This material is paramagnetic above 1.8 K and exhibits an ambient-temperature electrical conductivity of σ295 K = 1.14(3) × 10-13 S cm-1 (Ea = 0.74(3) eV). Upon soaking in a solution of sodium naphthalenide and 1,2-dihydroacenaphthylene, this compound undergoes a single-crystal-to-single-crystal (SC-SC) reduction to give Na3(Me4N)2[Mn2L3]. Structural and spectroscopic analyses confirm this reduction to be ligand-based, and as such the anionic framework is formulated as [MnII2(L3-)3]5-. Magnetic measurements confirm that this reduced material is a permanent magnet below Tc = 41 K and exhibits a conductivity value of σ295 K = 2.27(1) × 10-8 S cm-1 (Ea = 0.489(8) eV), representing a remarkable 200 000-fold increase over the parent material. Finally, soaking the reduced compound in a solution of [Cp2Fe]+ affords Na(Me4N)[MnII2(L2-)3] via a SC-SC process, with magnetic and electrical properties similar to those observed for the original oxidized material. Taken together, these results highlight the ability of metal benzoquinoid frameworks to undergo reversible, simultaneous redox switching of magnetic order and electrical conductivity.

scholarly journals Reversible redox switching of magnetic order and electrical conductivity in a 2D manganese benzoquinoid framework

2020 ◽  
Author(s):  
Lujia Liu
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Single Crystal ◽  
Magnetic Order ◽  
Magnetic Measurements ◽  
Fold Increase ◽  
Parent Material ◽  
Formidable Challenge ◽  
Redox Switching ◽  
Magnetic And Electrical Properties

© 2019 The Royal Society of Chemistry. Materials with switchable magnetic and electrical properties may enable future spintronic technologies, and thus hold the potential to revolutionize how information is processed and stored. While reversible switching of magnetic order or electrical conductivity has been independently realized in materials, the ability to simultaneously switch both properties in a single material presents a formidable challenge. Here, we report the 2D manganese benzoquinoid framework (Me4N)2[MnII2(L2-)3] (H2L = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinone), as synthesized via post-synthetic counterion exchange. This material is paramagnetic above 1.8 K and exhibits an ambient-temperature electrical conductivity of σ295 K = 1.14(3) × 10-13 S cm-1 (Ea = 0.74(3) eV). Upon soaking in a solution of sodium naphthalenide and 1,2-dihydroacenaphthylene, this compound undergoes a single-crystal-to-single-crystal (SC-SC) reduction to give Na3(Me4N)2[Mn2L3]. Structural and spectroscopic analyses confirm this reduction to be ligand-based, and as such the anionic framework is formulated as [MnII2(L3-)3]5-. Magnetic measurements confirm that this reduced material is a permanent magnet below Tc = 41 K and exhibits a conductivity value of σ295 K = 2.27(1) × 10-8 S cm-1 (Ea = 0.489(8) eV), representing a remarkable 200 000-fold increase over the parent material. Finally, soaking the reduced compound in a solution of [Cp2Fe]+ affords Na(Me4N)[MnII2(L2-)3] via a SC-SC process, with magnetic and electrical properties similar to those observed for the original oxidized material. Taken together, these results highlight the ability of metal benzoquinoid frameworks to undergo reversible, simultaneous redox switching of magnetic order and electrical conductivity.

scholarly journals Reversible redox switching of magnetic order and electrical conductivity in a 2D manganese benzoquinoid framework

2019 ◽  
Vol 10 (17) ◽  
pp. 4652-4661 ◽  
Author(s):  
Lujia Liu ◽  
Jordan A. DeGayner ◽  
Lei Sun ◽  
David Z. Zee ◽  
T. David Harris
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Order ◽  
Reversible Redox ◽  
Redox Switching

We report a 2D manganese benzoquinoid network that undergoes simultaneous redox switching of magnetic order and electrical conductivity.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

Total Body Electrical Conductivity Measurements in the Neonate

1991 ◽  
Vol 18 (3) ◽  
pp. 611-627 ◽  
Author(s):  
Marta L. Fiorotto ◽  
William J. Klish
Keyword(s):  
Electrical Conductivity ◽  
Conductivity Measurements ◽  
Total Body

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

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