Kinetics of 4He gas sorption by fullerite C60. Quantum effects

The kinetics of helium gas sorption by a C60 powder and subsequent desorption of the 4He impurity from the saturated powder has been investigated in the temperature interval T = 2-292 K. Evidence is obtained that supports the existence of two stages in the temperature dependences of sorption and desorption. The stages account for the different times taken by helium to occupy the octahedral and tetrahedral interstices in the C60 lattice. The characteristic times of sorption and desorption coincide. It is found that the temperature dependences of the characteristic times of occupying the octahedral and tetrahedral interstices are nonmonotonic. As the temperature is lowered from 292 K to 79.3 K, the characteristic times increase, which indicates a predominance of thermally activated diffusion of helium in C60. On a further decrease to T = 10 K the characteristic times reduce over an order of magnitude. Below 8 K the characteristic times of sorption and desorption are temperature-independent. This suggests a tunnel character of 4He diffusion in C60.Comment: 6 pages, 2 figure

The effect of O2 impurities on the low temperature radial thermal expansion of bundles of closed single-walled carbon nanotubes

The effect of oxygen impurities upon the radial thermal expansion (ar) of bundles of closed single-walled carbon nanotubes has been investigated in the temperature interval 2.2-48 K by the dilatometric method. Saturation of bundles of nanotubes with oxygen caused an increase in the positive ar-values in the whole interval of temperatures used. Also, several peaks appeared in the temperature dependence ar(T) above 20 K. The low temperature desorption of oxygen from powders consisting of bundles of single-walled nanotubes with open and closed ends has been investigatedComment: 7 pages, 3 figure

Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 4He

The radial thermal expansion (ar) of bundles of single-walled carbon nanotubes saturated with 4He impurities to the molar concentration 9.4% has been investigated in the interval 2.5-9.5 K using the dilatometric method. In the interval 2.1-3.7 K (ar) is negative and is several times higher than the negative (ar) for pure nanotube bundles. This most likely points to 4He atom tunneling between different positions in the nanotube bundle system. The excess expansion was reduced with decreasing 4He concentration.Comment: 4 pages, 1 figure, will be published in Fiz.Nizk Temp. #7, 201

Environmental Resource - Economized Processes of Recycling Mineral Raw Materials of Complex Composition

The results of the studies on the justification of technological processes providing recycling of the warehoused ferruginous quartzites of complex composition and waste non-ferrous metals allowing to receive additional commodity products are given. The example of amphibole and biotite varieties of ferruginous quartzites of CMA and tailings of copper-zinc sulphide Ural ores determines the reasons of ineffective use of traditional technology solutions for recycling. The reasons of environmental hazards concerning varieties of technogenic mineral substances to the environment are identified. The presence in ferruginous quartzites complex composition of various silicates, carbonates and iron sulphides change their technological properties. So to get the iron concentrate from them suggests a new combination of technological operations performed in specially selected operating conditions. The specifics of the presence of mineral components in solid mineral wastes of nonferrous metal ores indicates the possibility of obtaining additional marketable products. With the use of laboratory multiscale modelling and physical methods of analysis regularities of variation of fractionation, separation and mineral concentration operations efficiency by varying its composition and the various influencing factors are identified. To improve the efficiency of the individual technological operations it is recommended to use different techniques, using physical and physico-chemical effects on the polymineral systems. The flow diagrams for the considered varieties of technogenic processing of mineral substances, allowing them to obtain standared quality products (metal-containing concentrates), and the results of their testing are submitted. The suggested technological solutions can reduce the amount of environmentally hazardous mineral substance, hosted in technogenic formations