32 research outputs found
Magnetic properties of polymerized C with Fe
We provide evidence that high-pressure high-temperature (2.5 GPa and 1040 K)
treatment of mixtures of iron with fullerene powders leads to the complete
transformation of iron into iron carbide FeC. The comparison of the
magnetic properties (Curie temperature and magnetic moment) of the here studied
samples and those for the ferromagnetic polymer Rh-C indicates that the
main ferromagnetic signal reported in those samples is due to FeC and not
related to the ferromagnetism of carbon as originally interpreted. Taking into
account the results obtained in this study the original paper on ``Magnetic
carbon" (Nature {\bf 413}, 716 (2001)) was recently retracted.Comment: 5 Figures, 4 page
Magnetic properties of carbon phases synthesized using high pressure-high temperature treatment
Two sets of samples were synthesized at 3.5 GPa near the point of C60 cage
collapse at different annealing times. A clear structural transformation from
mixture of C60 polymeric phases to graphite-like hard carbon phase was
confirmed by X-ray diffraction and Raman spectroscopy. Magnetic force
microscopy and superconducting quantum interference device were used to
characterize the magnetic properties of the synthesized samples. We found that
the sample preparation conditions used in this study are not suitable to
produce bulk magnetic carbon.Comment: 26 pages, 7 figure
Scanning tunnelling microscopy on organic field-effect transistors based on intrinsic pentacene
Childhood pesticide poisoning in Zhejiang, China: a retrospective analysis from 2006 to 2015
Solution-processing of semiconducting organic molecules for tailored charge transport properties
We studied the charge transport characteristics of the organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) deposited by dip-coating of a solution in an azeotropic solvent mixture. Arrays of crystalline ribbons were obtained with a morphology controllable by variation of the coating speed U. The charge carrier mobility µ exhibited a systematic and reproducible dependence on the coating speed U and maximum values as high as µ ˜ 1.0 cm2/(V s)
Solution Processing of Semiconducting Organic Molecules for Tailored Charge Transport Properties
Characterization of phases synthesized close to the boundary of C60 collapse at high temperature high pressure conditions
Two sets of samples were synthesized at high pressure high temperature conditions in the P–T region where C60 molecules collapse into a nearly amorphous graphite-like hard carbon phase. For the first set, heating temperature was varied at fixed pressure and preparation time. For the second set, synthesis time was varied at fixed pressure and fixed temperature. Detailed structural characterization of samples was performed using Raman spectroscopy and powder XRD. Mechanical properties of the samples have been studied by nanoindentation method. It has been found that duration of heat treatment under high pressure is an important parameter which influences the temperature of fullerene cage collapse. Both tetragonal and rhombohedral polymeric phases transform into hard carbon phase over a rather narrow temperature interval, but the tetragonal phase shows somewhat increased stability against C60 collapse. Viscoelastic mechanical behavior during nanoindentation was observed for fullerene polymers but not for graphite-like hard carbon phase. Possible mechanism for nucleation of the hard carbon phase in polymeric C60 networks is discussed
Salt concentration effects in planar light-emitting electrochemical cells
Incorporation of ions in the active layer of organic semiconductor devices may lead to attractive device properties like enhanced injection and improved carrier transport. In this paper, we investigate the effect of the salt concentration on the operation of light-emitting electrochemical cells, using experiments and numerical calculations. The current density and light emission are shown to increase linearly with increasing ion concentration over a wide range of concentrations. The increasing current is accompanied by an ion redistribution, leading to a narrowing of the recombination zone. Hence, in absence of detrimental side reactions and doping-related luminescence quenching, the ion concentration should be as high as possible