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The fractal structure of porous carbon materials (PCMs) obtained by hydrothermal carbonization of plant raw materials in the temperature range of 600 ÷ 1100 °С is investigated using the low-temperature porometry method. It is set that materials with a developed microporous structure and a surface fractal dimension of 2.58 are formed at carbonization temperatures of 600 ÷ 800 °C. At higher carbonization temperatures, the value of the fractal dimension of the surface decreases to 2.17, which indicates the formation of an almost smooth surface due to the intensive removal of carbon atoms from the surface layers of the material particles, a decrease in the number of micropores with their transition to mesopores, the combination of small carbon clusters in larger and the formation of microparticles of non-porous carbon material. [ABSTRACT FROM AUTHOR]

The structure, morphology and conductive properties of C-Al2O3 composite materials depending on the percentage content of the oxide phase are investigated using small-angle X-ray scattering, lowtemperature porometry and impedance spectroscopy. It has been found that the structure of the explored materials is formed by mass fractals as a result of the carbon cluster aggregation on the surface of alumina particles. The reduction in the fractal dimension from 2.80 to 1.90 and the corresponding loosening of the structure are due to the reduction of the carbon phase volume in the composite material. Increase in the percentage content of the oxide component also leads to an increase in the porosity (from 0.62 to 0.80), a decrease in the total (from 424 to 300 m2/g according to the small-angle X-ray scattering) and open (from 356 to 14 m2/g according to the low-temperature porometry) specific surfaces and increase in the volume fraction of mesopores from 51 to 70 %. Addition to the carbon precursor of the oxide component results in a decrease in the electrical conductivity from 26.2 Ohm–1∙m–1 (for pure carbon material) to 0.4 Ohm–1∙m–1 (at 30 % Al2O3 content) due to the formation of additional barriers to electron pathways in the form of alumina particles parallel to a branched pore system in the carbon matrix. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Structure porosity and specific surface area of undoped and doped nanodispersed titanium dioxide with Zr, Nb was investigated. The porous structure of TiO2 is caused by its intervals between nanoparticles and their agglomerates. Surface morphology of obtained materials was determined by isotherms of nitrogen adsorption-desorption. Specific surface area of nanodispersed titanium dioxide, according to the results, consists 182 m²/g. It was found, that during doping of titanium dioxide with zirconium comparing to origin TiO2 specific surface increases in 30 %, and for niobium-doped decreases in 20 %. Pore-size distribution for TiO2 correspond to the value of 10-15 nm. [ABSTRACT FROM AUTHOR]