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X-ray diffraction (XRD) studies of the phases formed on the surface of the Li-doped PbFe0.5Nb0.5O3 (PFN) ceramics sintered under different conditions from the mechanically activated mixture of oxides and Li2CO3 have been carried out. At sintering temperatures exceeding 800°C a partial evaporation of PbO leads to the formation of pyrochlore Pb2Fe4Nb4O21 and lithium ferrites LiFeO2 and LiFe5O8 phases in the surface layer about 100 μm thick. An increase of the Neel temperature by more than 40 K, as compared to single crystal, was achieved in the mechanically activated PFN powder sintered at 600°C.

The effect of high-energy mechanical activation on magnetic phase transition temperature TM of PbFe0.5Nb0.5O3, PbFe0.5Ta0.5O3, and BaFe0.5Nb0.5O3 perovskites has been studied. Mossbauer studies have shown that TM values in all the perovskites studied can be changed substantially by mechanical activation and subsequent annealing. The increase of TM by 40-50 K, as compared to corresponding single crystals and ceramics sintered from the non-activated powders, was achieved in the mechanoactivated powders of both lead-containing and lead-free perovskites studied.

The effect of high-energy mechanical activation on dielectric and magnetic properties of PbFe1/2Ta1/2O3 (PFT) multiferroic was studied. Mossbauer studies have shown that the Neel temperature TN of the antiferromagnetic phase transition in PFT powders can be changed substantially by mechanical activation and subsequent annealing. The increase of TN by more than 70 K, as compared to PFT single crystal, was achieved in the mechanically activated PFT powder annealed at 700°C. Dielectric studies have shown that in contrast to ceramics obtained by usual sintering, PFT ceramics fabricated by sintering of the mechanoactivated powder does not show the relaxor-like behavior.

Optimal sintering temperature of PbFe1/2Nb1/2O3 (PFN) ceramics is 1120–1150°C, but ceramics sintered in this temperature range have low resistivity and high losses. Mechanochemical synthesis allows one to lower the optimal sintering temperature of PFN ceramics down to 1000°C, however dielectric losses remain high and the permittivity exhibits large frequency dispersion. In the present work it has been found that similar to the case of the routine solid state synthesis, Li doping enables one to reduce dramatically the losses of the PFN ceramics obtained by sintering the mechanochemically synthesized powders.

A thermal explosion and self-propagating high-temperature synthesis in low-calorific SiO2-Al mixtures subjected to preliminary mechanical activation are obtained. Results of x-ray and electron-microscopic investigations of the microstructure and phase composition of activated mixtures and reaction products are reported. It is found that complete reduction of quartz by aluminum occurs only in the thermal explosion mode.

Using the phenomenon of nondestructive ablation, a promising technique has been developed to determine the fractional composition of mixtures of nanoparticles having various origins; it consists of the ablation of the initial material by the laser radiation of a THz-range with the subsequent registration of disperse products in gas phase with the help of modern aerosol tools. In this work we present the results of studying a sample of MgAl2O4 spinel. The average size of nanoparticles determined by the method of nondestructive ablation amounts to 9 ± 1 nm, which corresponds to the data of powder X-ray diffraction. Using nondestructive ablation, a fraction of fine aggregates of particles remaining after the sputtering of powder is additionally registered. It is shown that nondestructive ablation is a rather quick method for measuring the size of particles.

Monophase and polyphase ceramic materials based on Magneli phases of titanium oxides of composition Ti3O5, Ti4O7, Ti5O9, and Ti6O11 were synthesized. The materials were obtained by mechanical activation of rutile with titanium and additives of niobium, vanadium, and iron, with subsequent sintering both in reductive atmosphere (hydrogen) and in neutral atmosphere (argon) in the temperature interval of 1060-1080?C. The dependences of the potentials of the obtained ceramic samples on time and composition during anodic polarization at current density of 5A/dm2 in a 1M solution of sulfuric acid were investigated. We developed a technique for manufacturing anodes in the form of hollow cylinders 60 mm in diameter with a wall 5 mm thick, and flat discs more than 60 mm in diameter.

The possibility of obtaining the TiO compound during mechanical activation of rutile and titanium in a planetary mill was studied depending on ball size and the activation time. The initial substances, TiO2 (rutile) and Ti (metal), were shown to change into TiO almost completely during grinding as early as after ten minutes. In this case the cubic modification of TiO formed, with the lattice parameter a=4.185(7) ? and particles of 1-3 ?m, which consisted of units about 10 nm in size. The other subject of our research was the dependence of the conductivity of the products on the conditions under which they were moulded and sintered under argon. The conductivity of the samples was in the range 300 to 600 S cm-1. Their chemical resistance equaled that of Ti4O7 samples.

Moistening of filler particles with binder, curing, and high-temperature synthesis were studied in a liquid-glass formulation based on aluminum oxide. Selected kinetic parameters of these processes were determined. The influence exerted by the phase composition and mechanical activation on the adhesion, yield of the synthesis product, and basic properties of the formulation were analyzed.

The possibility of using finely dispersed aluminum oxide for catalytic purification of effluent gases to remove noxious substances formed in calcination of coal blank parts in fabrication of graphite electrodes was studied.

Physicochemical processes that occur in mechanical activation of kaolinite in centrifugal-planetary mills in the presence of concentrated sulfuric acid were studied. A scheme of formation of aluminum sulfate in the course of acid activation was analyzed.

The results of investigation of mechanochemical reactions in the mixtures of hydroxides and carbonates of alkaline and alkaline earth metals with zirconium oxychloride and oxynitrate are presented. It is shown that one of the features of interaction between the components is the formation of the salts of alkaline and alkaline earth metals along with X-ray amorphous zirconium-containing compound. It is demonstrated that the mechanical activation of the mixture of yttrium carbonate and zirconium oxynitrate, followed by thermal treatment of this mechanically activated mixture, results in the formation of solid solution ZrO2-Y2O3 in cubic modification.

Structure formation in polytetrafluoroethylen subjected to polarization charge of nanosized filler is considered. The mechanism of polymer nanocomposites formation is suggested basing on the results of X-ray diffraction, electron microscopy and thermal electret studies.

The processes of phase formation by heating of a mechanically activated mixture of Ti + TiO2 in different atmospheres (air, argon, hydrogen) were investigated. The Ti4O7 compound was obtained by annealing of the mixture in hydrogen atmosphere in the interval of temperatures of 900-1200?C, the Ti2O3 oxide formed at 800?C in argon atmosphere and TiO2 formed in air atmosphere Conductivity and morphology of Ti4O7 samples obtained in hydrogen were studied.

The mechanochemical method was used for the synthesis of highly dispersed stoichiometric and nonstoichiometric LixMn2O4 spinel starting from different manganese (MnO2, Mn2O3, MnO) and lithium (LiOH, LiOH·H2O, Li2CO3) compounds. It is shown that the oxidation state of manganese greatly influences on the kinetics of mechanochemical reactions. On the other hand, different crystal structure and mechanical properties of initial lithium compounds result in different mechanisms of mechanochemical action on the activated mixtures. A strong effect of temperature and lithium content on the composition and lattice constant of the final products was found. Conductivity of LixMn2O4 spinels, measured by complex impedance spectroscopy, is likely caused by intergrain resistance. The activation energy of conductivity does not depend on x, the phase transition at 290±10 K, observed for stoichiometric spinel, is accompanied by a conductivity decrease. Test experiments in the electrochemical cell Li/LiPF6, EC/LiMn2O4,C demonstrate that lithium–manganese oxide obtained by the mechanochemical method is a promising cathode material for 4 V lithium batteries.

It has been established using X-ray photoelectron spectroscopy in combination with other physical methods that the initial stages of mechanochemical synthesis of LiMn 2 O 4 in mixtures of MnO 2 with LiOH and Li 2 CO 3 are considerably different. In the first case the “smearing” of LiOH, having a flaky structure, on the surface of MnO 2 and the formation of an amorphous layer take place. The reaction is accompanied by a redox process, with the participation of OH groups and Mn 4+ ions and with diffusion of lithium ions to the interior of the particles, and is completed by formation of Li–O–Mn bonds. No change in the valence state of manganese was detected, in Li 2 CO 3 , only brittle fracture was observed. Formation of defect spinel-like Li 2 O · y MnO 2 (2.5≤ y ≤4) on the surface is proposed.

The present work studies the effect of high-energy mechanical activation using the planetary-centrifugal ball mill AGO-2 and subsequent annealing on the synthesis and magnetic properties of PbFe0.5Nb0.5O3 (PFN). This technique enables one to perform the mechanically activated synthesis of PFN at much shorter time. The results of X-ray phase analysis, electron microscopic studies and transmission Mossbauer 57Fe spectra measurement are presented and discussed. Mossbauer studies show that the temperature of magnetic phase transition in PbFe0.5Nb0.5O3 powders can be changed by mechanical activation and subsequent annealing.

The effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described. At temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass. Within the high-temperature range heat-insulating properties are improved by the synthesis of nepheline in the reaction between sodium silicate and alumina. Mechanical activation of alumina improves this effect. Introduction of carbamide and boric acid additives improves the fireproof properties of the gaseous medium.

For highly dispersed α-Fe 2 O 3 the effect of mechanical activation in the high-powered ball mill under Ar atmosphere on its real structure and reactivity has been studied by using methods sensitive to the bulk (X-ray diffraction, TEM, IR spectroscopy of the lattice vibrations, static magnetic method) as well as to surface properties (SIMS, IR spectroscopy of adsorbed CO and surface hydroxyls, catalytic CO oxidation). Before activation, initial sample was shown to have a rather high density of surface and near-surface extended defects with local spinel structure probably stabilized by admixed sodium ions, while the bulk is free from such disturbances. Cooperative distortion of the lattice (increase of the distance between cation layers and some equalizing of the O–O distances in the anion sublattice) was observed and explained by an effect of the admixed sodium cations in the interstitial positions. Mechanical activation was found to generate anion vacancies in the bulk that was accompanied by a further increase of the distance between cation layers, whereas a mode of relaxation within the anion layers approaches that typical for the perfect hematite. A fall of the density of near-surface extended defects caused by mechanical activation was explained by the glide and/or climb mechanisms and was found to correlate with the decrease of the hematite reactivity.

Thermodynamic calculations have shown that chemical reactions in mixtures of hydrated oxides are more advantageous than those in anhydrous oxide mixtures. Mechanochemical reactions of calcium oxide with hydrated and anhydrous aluminum, silicon, titanium, vanadium, and tungsten oxides are investigated experimentally. It was shown that the reaction rate is correlated with the thermodynamic reaction potentials, and also with differences in the proton affinity of the oxides. The influence of water additives on the synthesis rate was investigated. It was found that the reaction rate goes through a maximum in its dependence on water content.

The effect of transition metal oxides and the sintering temperature on the strength parameters of cordierite ceramics synthesized using mechanical activation is investigated. It is established that an introduction of oxide additives improves the strength of ceramics.

New method of dispersed perovskites synthesis based upon mechanochemical activation of the solid starting compounds is elaborated. The influence of defect structure of these compounds as well as surface segregation on their catalytic properties is discussed. Basic stages of the monolith perovskite catalysts preparation are optimized. The experimental samples of monolith catalysts of various shapes are obtained, possessing high activity, thermal stability and resistance to catalytic poisons.

One of the requirements imposed on polishing materials is that an isometric form must be present in the abrasive grain (the crystallite). This condition is satisfied by aluminum–magnesium spinel, MgAl2O4, which crystallizes in cubic symmetry, forming crystallites of octahedral habit, and possesses satisfactory hardness. This paper describes a method of obtaining nanosize particles of spinel by mechanical activation of a mix of hydroxides at the stage preceding heat treatment at temperatures of 700–800 °C, significantly lower than those used in known methods of synthesizing spinel. Results are given that show that spinel has satisfactory polishing ability.

Experimental results on the influence of preliminary mechanical activation on the thermal decomposition of chalcopyrite are presented and discussed. The following experimental facts were found: 1. a decrease in the temperature of the endothermic DTA peak ofβ-CuFeS2 from 821 K for a non-activated sample to 763 K for an optimally activated one; 2. a decrease in the apparent activation energy of the thermal decomposition of CuFeS2 from 238 kJ mol−1 for a non-activated sample to 72 kJ mol−1 for an optimally activated sample.

Superparamagnetism has been observed in fine particles of nickel ferrite and ferric oxide, which were prepared by mechanical grinding in centrifugal planetary mills. The contribution of surface iron ions to the Mossbauer spectra has been evolved. The particle sizes have been estimated.