Carbon-based magnetism

Palacio F, Makarova T, editors. Carbon based magnetism an overview of the magnetism of metal free carbon-based compounds and material. Amsterdam, Netherlands Elsevier 2006. 

Enoki, T. and K. Takai. 2006. Unconventional magnetic properties of nanographite. In F. Palacio and T. Makorova (eds.), Carbon-Based Magnetism An Overview of the Magnetism of Metal Free Carbon-Based Compounds and Materials, pp. 397-416, Elsevier Science, London. 

Fig. 10. Temperature dependence of the magnetic susceptibility of various carbon-based materials. The data on HOPG (H//c) are taken at 200 Oe. The data reported for nanolubes, graphite (H in-plane), and diamond, were taken at 4 kOe, those on diamond at 8 kOe. The ordinate axis is negative (after Heremans et al.[26 ).

S. Centi, S. Laschi, M. Franek, and M. Mascini, A disposable immunomagnetic electrochemical sensor based on functionalized magnetic beads and carbon-based screen-printed electrodes (SPCEs) for the detection of polychlorinated biphenyls (PCBs). Anal. Chim. Acta 538, 205—212 (2005). 

Magnicol [Magnetic columnar] A process for making Alnico (an iron-based magnetic alloy containing Al, Ni, Co, and Cu) crystallize with a columnar grain structure in order to optimize its magnetic properties. Successive additions of silicon, carbon, and sulfur are made to the initial melt. 

The cyclopenta[6]quinolizidines are tabulated below. Mass, proton, and carbon-13 magnetic resonance and vapor-phase FTIR spectral data have been presented for 251F and its 0-acetate (152). The structure of 251F and tentative structures of the nine congeners also detected in Minyobates bombetes are shown in Fig. 18. Most show a base peak or major fragment at an odd mass (m/z 109, 111, 125, or 139). 

Chemical examination of Sarcophyton glaucum collected at Ishigaki island, Okinawa Prefecture, resulted in the isolation of seven cembranoid diterpenes, namely sarcophytol A (3), sarcophytol A acetate (4), sarcophytol B (5), sarcophy-tonin A (6), and minor constituents sarcophytol C (7), D (8), and E (9). These compounds were found to be susceptible to autooxidation while being purified. The structural determination of these compounds was made mainly based on proton and carbon nuclear magnetic resonance (NMR) spectral evidence and degradative studies by ozonolysis. X-ray crystallographic analysis for the two crystalline compounds, sarcophytol B (5) and D (8), has been reported. The total lipid extracts of S. glaucum comprise about 40% sarcophytol A (3), 5% each of sarcophytol A acetate (4) and sarcophytonin A (6), about 1% sarcophytol B (5), and minor amounts of sarcophytol C (7), D (8), and E (9). 

An interesting offshoot in the context of carbon-based nanomaterials is the role of external perturbations in modulating their physical and chemical characteristics. These perturbations can include cations or neutral atoms. In this context, we examined the magnetic properties of exohedral fullerenes of alkali metal fullerides (Aj,-C6o. A = Na, K, Rb, Cs) [148-150] and the spin properties of endohedral fullerenes (A C6o, A = N, P, As, O, S) [128,151] (Fig. 34.11). The most interesting aspect of the experimental... 

Interest in carbon-based composites with MNPs goes back a long way. Examples are the studies of magnetic properties of cobalt particles [55], electric and optical properties of layers with copper [56] or silver [57, 58] nanoparticles, and so on. It was found in optical absorption experiments that copper and silver nanoparticles [56, 58] dispersed in carbon matrices exhibit a weak SPR effect as in our work (Figures 8.4b, 8.6, and 8.7). 

In carbon, the conductivity varies from 10 (ohm-cm) for amorphous carbon to approximately 300 (ohm-cm) in the longitudinal direction for PAN-based high modulus carbon fibers. Apart from relatively low conductivity, carbon has the same magnetic permeahUity as aluminum, i.e., approximately 1. In order to obtain a given damping, carbon-based fillers have to he added in higher concentrations in comparison with metallic fillers such as steel. However, special carhon hlack grades with microporous structure and increased conductivity can now be found that allow the construction of a conductive network at relatively low concentrations. 

In the nanotechnology field, carbon-based materials and associated composites have received special attention both for fundamental and applicative research. In the first kind, carbon compounds may be included, often taking the form of a hollow spheres, ellipsoids, or mbes. Spherical and ellipsoidal carbon nanomaterials are referred to as fullerenes, while cylindrical ones are called nanombes and nanofibers. In the second class, one includes composite materials that combine carbon nanoparticles with other nanoparticles, or nanoparticles with large bulk-type materials. The unique properties of these various types of nanomaterials provide novel electrical, catalytic, magnetic, mechanical, thermal, and other features that are desirable for applications in commercial, medical, military, and enviromnental sectors. This is the case for conducting polymers (CPs) and carbon nanombes (CNTs) [1-5]. 

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