354 research outputs found
Huge Seebeck coefficients in non-aqueous electrolytes
The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium
nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in
1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range
from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few
hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here
we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium
nitrate in 1-dodecanol. These striking results open the question of
unexpectedly large kosmotrope or "structure making" effects of
tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy
Observation of superspin glass state in magnetically textured ferrofluid (gamma-Fe2O3)
Magnetic properties in a magnetically textured ferrofluid made out of
interacting maghemite (gamma-Fe2O3) nanoparticles suspended in glycerin have
been investigated. Despite the loss of uniform distribution of anisotropy axes,
a superspin glass state exists at low temperature in a concentrated, textured
ferrofluid as in the case of its non-textured counterpart. The onset of
superspin glass state was verified from the sample's AC susceptibility. The
influence of the anisotropy axis orientation on the aging behavior in the
glassy states is also discussed
Thermopower peak in phase transition region of (1-x)LaCaMnO/xYSZ
The thermoelectric power (TEP) and the electrical resistivity of the
intergranular magnetoresistance (IGMR) composite,
(1-x)LaCaMnO/xYSZ (LCMO/YSZ) with x = 0, 0.75%, 1.25%,
4.5%, 13% 15% and 80% of the yttria-stabalized zirconia (YSZ), have been
measured from 300 K down to 77 K. Pronounced TEP peak appears during the phase
transition for the samples of x 0, while not observed for x = 0. We suggest
that this is due to the magnetic structure variation induced by the lattice
strain which is resulting from the LCMO/YSZ boundary layers. The transition
width in temperature derived from , with being the AC magnetic
susceptibility, supports this interpretation.Comment: 4 pages, 4 eps figures, Latex, J. Appl. Phys 94, 7206 (2003
Intrinsic Low Temperature Paramagnetism in B-DNA
We present experimental study of magnetization in -DNA in
conjunction with structural measurements. The results show the surprising
interplay between the molecular structures and their magnetic property. In the
B-DNA state, -DNA exhibits paramagnetic behaviour below 20 K that is
non-linear in applied magnetic field whereas in the A-DNA state, remains
diamagnetic down to 2 K. We propose orbital paramagnetism as the origin of the
observed phenomena and discuss its relation to the existence of long range
coherent transport in B-DNA at low temperature.Comment: 5 pages, 4 figures, submitted to Physical Review Letters October 200
New Analytical Methods for the Surface/ Interface and the Micro-Structures in Advanced Nanocomposite Materials by Synchrotron Radiation
Analytical methods of surface/interface structure and micro-structure in advanced nanocomposite materials by using the synchrotron radiation are introduced. Recent results obtained by the energy-tunable and highly collimated brilliant X-rays, in-situ wide angle/small angle X-ray diffraction with high accuracy are reviewed. It is shown that small angle X-ray scattering is one of the best methods to characterize nanoparticle dispersibility, filler aggregate/agglomerate structures and in-situ observation of hierarchical structure deformation in filled rubber under cyclic stretch. Grazing Incidence(small and wide angle) X-ray Scattering are powerful to analyze the sintering process of metal nanoparticle by in-situ observation as well as the orientation of polymer molecules and crystalline orientation at very thin surface layer (ca 7nm) of polymer film. While the interaction and conformation of adsorbed molecule at interface can be investigated by using high energy X-ray XPS with Enough deep position (ca 9 micron m).Received: 11 October 2010; Revised: 13 December 2010; Accepted: 23 December 201
Noise Measurement of Interacting Ferromagnetic Particles with High Resolution Hall Microprobes
We present our first experimental determination of the magnetic noise of a
superspinglass made of < 1 pico-liter frozen ferrofluid. The measurements were
performed with a local magnetic field sensor based on Hall microprobes operated
with the spinning current technique. The results obtained, though preliminary,
qualitatively agree with the theoretical predictions of Fluctuation-Dissipation
theorem (FDT) violation [1].Comment: 4pages, 2 figure
Non-generality of the Kadowaki-Woods ratio in correlated oxides
An explicit expression for the Kadowaki-Woods ratio in correlated metals is
derived by invoking saturation of the (high-frequency) Fermi-liquid scattering
rate at the Mott-Ioffe-Regel limit. Significant deviations observed in a number
of oxides are quantitatively explained due to variations in carrier density,
dimensionality, unit cell volume and the number of individual sheets in the
Brillouin zone. A generic re-scaling of the original Kadowaki-Woods plot is
also presented.Comment: 9 pages of text, 1 table, 2 figure
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