Search results for "Magnetism"

Mechanical properties and water vapor permeability of starch/montmorillonite nanocomposites

2009

Results of an investigation into an unmodified-montmorillonite (MMT)-filled nanocomposite based on plasticized starch are reported. Data on the influence of MMT content on the tensile mechanical properties of the material are presented. Particular attention is given to the water vapor permeability of the nanocomposite. It is found that the resistance to water permeation of plasticized starch can be improved considerably by introducing a rather small amount of the filler into it. Data on the influence of MMT content on the coefficients of moisture diffusion, solubility, and permeability are reported. Also, a simple method for determining the effect of irregularly oriented platelike filler pa…

One‐Pot Synthesis of Superparamagnetic CoO‐MCM‐41 Nanocomposites with Uniform and Highly Dispersed Magnetic Nanoclusters

2004

Superparamagnetic CoO-MCM-41 mesoporous nanocomposites, with variable cobalt amounts, in the form of well-dispersed CoO-like clusters, were prepared in a large compositional range by a one-step reproducible procedure employing co-hydrolysis and co-condensation of the inorganic precursors in a water/triethanolamine medium. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Optical, structural and electrical characterization of GaN/AIN nanoestructures : Quantum wells, quantum dots and nanowires

2011

Optofluidic taming of a colloidal dimer with a silicon nanocavity

2014

International audience; We report here the optical trapping of a heterogeneous colloidal dimer above a photonic crystal nanocavity used as an on-chip optical tweezer. The trapped dimer consists of a cluster of two dielectric microbeads of different sizes linked by van der Waals forces. The smallest bead, 1 μm in diameter, is observed to be preferentially trapped by the nanotweezer, leaving the second bead untrapped. The rotational nature of the trapped dimer Brownian motion is first evidenced. Then, in the presence of a fluid flow, control of its orientation and rotation is achieved. The whole system is found to show high rotational degrees of freedom, thereby acting as an effective flow-se…

Dynamic nuclear polarisation of biological matter

1986

Polarised targets as used in high energy physics experiments may be of considerable interest in biological structure research using polarized neutrons. So far, this promising method has been facing difficulties in getting reasonable polarization of the target nuclei. We report on a polarized "frozen spin" target which has been prepared from an enzyme dissolved in a mixture of heavy water and deuterated propanediol doped with a completely deuterated paramagnetic radical. Clusters of 700 protons defined by the structure of lysozyme embedded in a fully deuterated matrix were polarized to 75% within an hour by 4 mm microwave irradiation in a magnetic field of 2.5 tesla at a temperature of 0.3 K…

Hybrid Magnetic Multilayers by Intercalation of Cu(II) Phthalocyanine in LDH Hosts

2012

The intrinsic flexibility of layered double hydroxides (LDHs) has been here exploited to design hybrid multilayered materials by intercalation of the copper phthalocyaninetetrasulfonate (CuPcTs) complex in the interlamellar space offered by these layered hosts through a simple anion-exchange procedure. Taking advantage of their chemical versatility, two different LDHs, the diamagnetic ZnAl and the ferromagnetic NiAl, have been synthesized and characterized to explore the differences in the magnetic properties of the hybrids introduced by the intercalation of the paramagnetic complex.

Alternating antiferromagnetic and ferromagnetic exchange interactions in the S = 1 Heisenberg chain. Theory and magnetic properties

1997

Abstract We focus on the magnetic properties of the S = 1 Heisenberg chain with alternating antiferromagnetic and ferromagnetic exchange interactions J 1 and J 2 . The magnetic behavior of this system is calculated as a function of the alternation parameter α = J 2 /| J 1 |, from a general numerical procedure based on closed spin chains of increasing length. These theoretical results are fitted to rational unified expressions, which are subsequently used to describe the magnetic behavior of a nickel (II) complex, [Ni(bipy)(N 3 ) 2 ] n , exhibiting an alternating chain structure with a dominant ferromagnetic exchange.

Polynitrile anions as ligands: Synthesis, structure and magnetic properties of a new three-dimensional coordination polymer with the 2-dicyanomethyle…

2005

cited By 12; International audience; Reaction between CuCl2 and K2tcpd (tcpd2- = C[C(CN)2]32- = 2-dicyanomethylenc-1,1,3,3-tetracyanopropanediide anion) in presence of the neutral ligand tn (1,3-diaminopropane) in aqueous solution yields the new compound [Cu(tn)(tcpd)] (1) which was characterized by X-ray crystallography. The crystal structure of 1 consists of one [Cu(tn)]2+ unit and one tcpd2- anion, both located on general positions. Each Cu atom presents an essentially octahedral coordination with four nitrogen atoms arising from four polynitrile ligands and two nitrogen atoms from the chelating tn ligand. Despite its six nitrile groups potentially bridging, the tcpd ligand acts with a μ…

Synthesis, X-ray crystal structure and magnetic study of a μ 1,5-dca bridged ferromagnetic dimeric copper(II) complex

2008

Reaction of Cu(NO3)2 · 3H2O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL1), LiClO4, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu2(L1)2 (μ1, 5-dca)](ClO4) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand (HL1) occupy three coordination sites of the square plane while the remaining site is occupied by the nitrogen of a terminal nitrile of the bridging dca. The nitrogen of the other terminal nitrile group of the μ1,5-dca ligand…

Hexachlororhenate(IV) salts of organic radical cations

2005

Abstract The ionic salts ( p -rad) 2 [ReCl 6 ] ( 1 ) and ( m -rad) 2 [ReCl 6 ] ( 2 ) ( p / m -rad = 2-(4/3- N -methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazol-1-oxyl-3- N -oxide) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The nitronyl nitroxide cations in compound 1 show a layered disposition, whereas the [ReCl 6 ] 2− units are placed between these layers. The nitronyl nitroxide cations in compound 2 adopt an hexagonal array but they do not result in layers. Bulk magnetic properties of 1 and 2 have been investigated in the temperature range 2–300 K. Both compounds show weak but significant intermolecular antiferromagnetic …