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Samgin A.L.,RAS Institute of High Temperature Electrochemistry
Solid State Communications

This communication is inspired by recent results on the observation of "giant" rates for proton transfer in rutile TiO 2 at low temperatures in pump-probe experiments. An important point is that this is not a tunneling effect. We show that this classical looking effect has a quantum mechanical origin and may be called lattice-assisted hopping. To explore the possibility of formulating transport properties in terms of mode vibrations, we use a "quantum" fluctuationdissipation theorem, thus providing a concept of dynamic activation energy for ion hopping, which had been used in the above experimental study, rather heuristically, to fit the low-temperature "over the barrier" motion data. The resulting expression of hopping activation energy is more general than the standard one defined in units of kBT and is able to describe the crossover from the high to low-temperature regime of proton jumps. © 2012 Elsevier Ltd. All rights reserved. Source

This paper describes an empirically demonstrated mechanism of UO 2-ZrO2 cathode deposit formation during the (NaCl-KCl)equim.-UO2Cl2-ZrCl4 melts electrolysis. The first layer of the cathode product was formed through UO 2 2+ ion reduction to uranium dioxide followed by an exchange reaction with Zr4+ ions, which are present in the electrolyte. The subsequent reactions proceeded through simultaneous reduction and exchange reactions at the cathode. © 2013 Elsevier Ltd. All rights reserved. Source

Muzyukin I.L.,RAS Institute of High Temperature Electrochemistry
IEEE Transactions on Plasma Science

Fluxes of ions and electrons from plasma of a nanosecond high-voltage vacuum spark have been studied. Differences in the determination of the plasma expansion velocities by the probe method, the method of recording the flux of particles, and the Thomson spectrometer have been established. It has been shown that the spectrum of explosive emission electrons includes a high-energy part with energies higher than the discharge voltage. It has been assumed that the plasma stream contains high-energy electrons formed by intensive plasma oscillations. © 2011 IEEE. Source

Galashev A.Y.,RAS Institute of High Temperature Electrochemistry
Journal of Physical Chemistry C

Most sorbents display poor capacity for elemental mercury at elevated temperatures. Graphene is the potential candidate among different high-temperature sorbents. We have studied the physical properties of mercury films on partially hydrogenated imperfect graphene, as well as their heating and bombardment with xenon clusters, by means of molecular dynamics. Hydrogenated edges of a graphene sheet containing Stone-Wales defects withstand heating to 1100 K. Formation of the droplet leads to a decrease in the blunt contact angle. The bombardment of a target with a Xe13 cluster beam at energies of 5-30 eV and incidence angles of 0-60° aiming to remove a mercury film from imperfect graphene has been performed. The graphene is completely cleaned of mercury at a cluster energy of EXe ≥ 15 eV. Mercury is removed from the graphene film via sputtering of single atoms and droplet detachment. A stress in graphene resulting from forces normal to the sheet plane is noticeably higher than that due to forces acting in its plane. Bombardment at an angle of incidence of 45° is the most efficient and leads to lower graphene roughness. Thus, mercury can be removed from graphene by heating or bombarding with heavy noble gas clusters. © 2016 American Chemical Society. Source

Samgin A.L.,RAS Institute of High Temperature Electrochemistry
Journal of Physics and Chemistry of Solids

Stimulated diffusion of protons in oxides such as ABO3 crystals and rutile TiO2 is discussed in the context of quantum Brownian motion. A self-consistent lattice-assisted proton hopping (LAPH) model is developed by going from white noise (characteristic of the standard stochastic theory of superionic conduction) to colored noise in the Markovian limit. This model differs from the commonly used ion jump models in that the hydrogen diffusion rate prefactor is identified as a quantity proportional to the frequency of phonon assistance. Application of the quantum fluctuation- dissipation theorem suggests that the dynamic activation energy for diffusion is a function of a bath-mode frequency. The LAPH model can predict enhanced rates of barrier jumping at room temperature compared to thermally activated proton diffusion. This indicates that low-temperature solid oxide devices are potential candidates for use in hydrogen energy research. The LAPH model offers a valid explanation for the mechanism of high protonic mobility recently observed for TiO2 in a picosecond transient pump-probe experiment. This unexpected dominant lattice relaxation channel must be considered as a new classical-like (but low-temperature) proton transfer mechanism. For vibration-assisted protonic jumps to occur at low temperature, the phonon assistance must be classified as a low-frequency vibration specific to each lattice. © 2013 Elsevier Ltd. Source

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