No abstract available

[en] Research into a new method for separating palladium from rhodium, based on radiochemical principles, necessitated a re-investigation of the Gmelins Handbuch data indicating that Rh has allotropes. Two independent and different methods were used, which both yielded the same results; i.e. that no allotropy can be found. Non-ambient temperature X-ray diffraction (HT-XRD) did not show any difference in the diffractograms due to phase transformation of Rh-metal at elevated temperatures. Differential thermal analysis (DTA) confirmed the HT-XRD result in the temperature range of 1000-1400 deg C. In conclusion, the absence of allotropy of the metal rhodium was proven. (author)

[en] Published data on the new carbon nanomaterial, graphene, are described systematically from the chemist's standpoint. The attention is focused on the chemical methods of the synthesis of graphene-like materials from various precursors: natural and expanded graphite, graphite oxide, graphite intercalation compounds, etc. Approaches to the chemical modification of the graphene plane by various reagents and routes for the preparation of colloidal dispersions of graphene are considered. The bibliography includes 220 references.

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[en] Existing polytype notations have been critically examined to select a single notation which can describe the CdI₂ structures completely and most conveniently. A comparative study shows that the Zhdanov notation fulfils both the conditions. However, the ambiguities in the similar looking symbols is removed by employing some simple criteria proposed by Jain and Trigunayat for deciding the equivalent structures. Further, being numerical in nature this is the easiest notation to handle. (author)

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[en] We propose a novel lithography process in which ion induced phase transfomations of diamond form sacrificial layers allowing the fabrication of small structures including micro-electromechanical systems (MEMS). We have applied this novel lithography to the fabrication of diamond microcavities, cantilevers and optical waveguides. In this paper we present preliminary experiments directed at the fabrication of suspended diamond disks that have the potential for operation as optical resonators. Such structures would be very durable and resistant to chemical attack with potential applications as novel sensors for extreme environments or high temperature radiation detectors. (author). 3 refs., 3 figs

[en] Full text: After discovering fullerenes in 1985 and nanotubes later in 1991 one could speculate about the new allotrope state of carbon-frame structure consisted allometry from carbon atoms. Before just two allotrope structures were known - diamond and graphite; but the third form is a huge (sometimes enormous) molecules that has a unique physical and chemical properties. For instance, it is one hundred times crash-proved than steel, but weights just one sixth of the one. Though nanotubes properties are similar to the conductor's, but if nano-tube has a structure defect (one carbon six angle would be replaced by pentagons) we can produce a semiconductor belt. If to locate inside nanotubes the whole chain from fullerenes with already inserted in them by atoms of gadolinium, we receive a semiconductor. We offer a new and cheap method of obtaining of nano-tubes at an etching of catalytic agents. The essence of carbides in the mechanism of derivation of carbonaceous deposition on dispersible particles of metals is described by common scheme. According to this mechanism at interaction of hydrocarbons with oxides there is restoring metals, which again interacting with hydrocarbons, will generate acetylide(carbides). The decay last again is carried on to derivation by ferrous and free carbonium, on the basis of which the carbonaceous deposition of various frame can be shaped, including the nanotubes

[en] Based on theoretical and experimental observations, it has been established that the polytypes 2H and 4H act as basic structural units as regard to the formation of CdI₂ polytypes. As a result of this, some general rules have been formulated which help understand (i) the nature of restrictions in the close-packed arrangements and to deduce the genuine CdI₂ polytypes, and (ii) the classification of CdI₂ polytypes into various possible groups. This further helps to conclude that (i) the CdI₂ polytypes are simply a consequence of restrictions in the close-packed arrangements, (ii) the concept of stacking fault is superfluous as far as the formation of ordered polytypes are concerned, and (iii) the identification of CdI₂ polytypes on the basis of intensity data has limited implications unless some practical use of polytypes are found. (author)

No abstract available