1,639 research outputs found
Lattice expansion and non-collinear to collinear ferrimagnetic order in MnCrO nanoparticle
We report magnetic behaviour of MnCrO, which belongs to a special
class of spinel, known as chromite. Bulk MnCrO shows a sequence of
magnetic states, which follows paramagnetic (PM) to collinear ferrimagnetic
(FM) state below T 45 K and collinear FM state to non-collinear FM
state below T 18 K. The non-collinear spin structure has been
modified on decreasing the particle size, and magnetic transition at T
decreases in nanoparticle samples. However, ferrimagnetic order is still
dominating in nanoparticles, except the observation of superparamagnetic like
blocking and decrease of spontaneous magnetization for nanoparticle. This may,
according to the core-shell model of ferrimagnetic nanoparticle, be the surface
disorder effect of nanoparticle. The system also show the increase of T in
nanoparticle samples, which is not consistent with the core-shell model. The
analysis of the M(T) data, applying spin wave theory, has shown an unusual
Bloch exponent value 3.35 for bulk MnCrO, which decreases and
approaches to 1.5, a typical value for any standard ferromagnet, with
decreasing the particle size. MnCrO has shown a few more unusual
behaviour. For example, lattice expansion in nanoparticle samples. The present
work demonstrates the correlation between a systematic increase of lattice
parameter and the gradual decrease of B site non-collinear spin structure in
the light of magnetism of MnCrO nanoparticles
Extensional viscosity of copper nanowire suspensions in an aqueous polymer solution
Suspensions of copper nanowires are emerging as new electronic inks for
next-generation flexible electronics. Using a novel surface acoustic wave
driven extensional flow technique we are able to perform currently lacking
analysis of these suspensions and their complex buffer. We observe extensional
viscosities from 3 mPas (1 mPas shear viscosity) to 37.2
Pas via changes in the suspension concentration, thus capturing low
viscosities that have been historically very challenging to measure. These
changes equate to an increase in the relative extensional viscosity of nearly
12,200 times at a volume fraction of just 0.027. We also find that interactions
between the wires and the necessary polymer additive affect the rheology
strongly. Polymer-induced elasticity shows a reduction as the buffer relaxation
time falls from 819 to 59 s above a critical particle concentration. The
results and technique presented here should aid in the future formulation of
these promising nanowire suspensions and their efficient application as inks
and coatings.Comment: 7 pages, 5 figures, under review for Soft Matter RS
An organic channel structure formed by the supramolecular assembly of trithiocyanuric acid and 4,4'-bipyridyl
Trithiocyanuric acid (TCA) and 4,4'-bipyridyl (BP) form hydrogen-bonded co-crystals with aromatic compounds such as benzene, toluene, p-xylene and anthracene. The TCA-BP co-crystal is composed of cavities formed by the N-H···N hydrogen bonds between the two molecules, and the three-dimensional structure contains channels of approximately 10 Å where aromatic molecules are accommodated. The molar ratios of TCA, BP and the aromatic compound in the co-crystals are 2:1:1 or 2:1:0.5. Benzene, toluene and p-xylene are removed from the channels around 190, 183 and 170°C respectively, and these aromatic guests can be reintroduced into the empty channels of the apo-hosts. The apo-hosts with empty channels have reasonable thermal stability and exhibit shape selectivity in that the empty channels accommodate p-xylene but not m- or o-xylene or mesitylene
A novel hybrid layer compound containing silver sheetsand an organic spacer
A novel compound of the formula Ag2·CA (CA=cyanuric acid) possessing Ag sheets and hydrogen-bonded CA chains, exhibits anisotropic conductivity and acts as an infinite parallel plate capacitor with a high dielectric constant
Re-entrant spin glass and magnetoresistance in Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide
We have investigated the static and dynamic response of magnetic clusters in
Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide, where a sequence of magnetic
phase transitions, i.e., paramagnetic (PM) to ferromagnetic at T_{C}
270K and ferromagnetic to canted spin glass state at T_f\leq$ 125K is
observed
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