Effect of the Distribution of Manganese Ions on the Properties of Mn-Doped (Ba,Y)TiO3 PTCR Ceramics

The electrical properties and microstructure of (Ba,Y)TiO₃ PTCR ceramics were studied. The results indicate that the Mn ions increase the intergranular barrier height and produce a high-resistance layer on the grain surface. The temperature-dependent resistances of the grain bulk, surface layer, and grain boundaries, the temperature coefficient of resistance, and the magnitude of the varistor effect were assessed as a function of Mn content.     

Advantage of heat insulation made of materials with natural porosity

Various heat insulation materials produced at home and abroad are compared. The advantage of using natural nano-structured materials is substantiated. Translated from Novye Ogneupory, No. 7, pp. 41–44, July 2008.     

Catalytic properties of composite amorphous carbon-platinum layers in fuel cells

Catalytic properties of composite amorphous carbon-platinum layers produced by magnetron cosputtering have been studied. The layers were characterized by electron microscopy, IR spectroscopy, ellipsometry, gravimetry, and spectrophotometric chemical analysis. The catalytic activity of the layers was studied in an air-hydrogen fuel cell by measuring its load and power characteristics.     

Water transport and power network (WTPN) of the Russian Federation

A brief account of the concept developed in 1993 on orders of the Ministry of Fuel and Power of the Russian Federation by a group of authors: A. E. Asarin, T. P. Dotsenko, V. D. Novozhenin, G. L. Sarukhanov (State Planning, Surveying, and Research Institute), V. F. Samarin, R. P. Stepanov, V. I. Fedoryak, M. A. Shestopal (State River Transport Planning Institute), and A. A. Belyakov (Moscow State Construction University).     

Synthesis of nonstoichiometric aluminomagnesium spinel with a tetragonal lattice (review)

The results of x-ray diffraction and IR-spectroscopic studies of samples of nonstoichiometric aluminomagnesium spinel Mg_1?x Al_2?y O_4?z (OH)_z formed after treating aluminomagnesium spinel synthesized by the sol-gel method at temperatures of 800 and 1100°C with concentrated acids, are reported. It was found that three phases of nonstoichiometric aluminomagnesium spinel Mg_1?x Al_2?y O_4?z (OH)_z with tetragonal lattices and a different type of superstructure are formed. The x-ray patterns of the two phases correspond to body-centered lattices with parameters a = 5.712(3) Å, c = 8.092(3) Å, and a = 5.714(3) Å. The x-ray pattern of the third phase was indexed in a primitive tetragonal lattice: a = 5.718(3) Å, c = 24.261(27) Å.     

Forms of extraction of silicon compounds in rice husks

The forms of extraction of silicon compounds in rice husk, proposed as a source of silicon dioxide, were examined. A model in which the silica particles distributed in the plant cells of rice husk are separated by organic layers from mineralizer impurities was proposed. Crystallization of silicon dioxide begins after elimination of the layers of carbon formed at the site.