A new chemical oscillating reaction system:Diacetone\|BrO - 3\|Mn 2+ \|H 2SO 4 has been described.The best reaction condition and the reactant's concentrations have been reported. The effect of the reactio...A new chemical oscillating reaction system:Diacetone\|BrO - 3\|Mn 2+ \|H 2SO 4 has been described.The best reaction condition and the reactant's concentrations have been reported. The effect of the reaction temperature on the oscillation has been studied and the average activation energies of the reaction during the oscillation period Ep and the oscillatory life E L are obtained, E p=100.68 kJ·mol -1 , E L=48.05 kJ·mol -1 .The new characteristics of oscillation period have been investigated in detail. The intermediate and the end product of the oscillatory reaction is proposed and the possible mechanism have been analysed.展开更多
Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we p...Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we perform molecular dynamics（MD） simulations to study the frictional behavior of a diamond tip sliding over a graphite surface. In contrast to the common wisdom, our MD results suggest that the energy barrier associated lateral sliding（known as energy corrugation） comes not only from interaction between the tip and the top layer of graphite but also from interactions among the deformed atomic layers of graphite. Due to the competition of these two subentries, friction on graphite can be tuned by controlling the relative adhesion of different interfaces.For relatively low tip-graphite adhesion, friction behaves normally and increases with increasing normal load. However,for relatively high tip-graphite adhesion, friction increases unusually with decreasing normal load leading to an effectively negative coefficient of friction, which is consistent with the recent experimental observations on chemically modified graphite. Our results provide a new insight into the physical origins of energy corrugation in atomic scale friction.展开更多
文摘A new chemical oscillating reaction system:Diacetone\|BrO - 3\|Mn 2+ \|H 2SO 4 has been described.The best reaction condition and the reactant's concentrations have been reported. The effect of the reaction temperature on the oscillation has been studied and the average activation energies of the reaction during the oscillation period Ep and the oscillatory life E L are obtained, E p=100.68 kJ·mol -1 , E L=48.05 kJ·mol -1 .The new characteristics of oscillation period have been investigated in detail. The intermediate and the end product of the oscillatory reaction is proposed and the possible mechanism have been analysed.
基金support from the National Natural Science Foundation of China (Grants 11272177, 11422218, 11432008)the National Basic Research Program of China (Grants 2013CB933003, 2013CB934201 and 2015CB351903)+2 种基金the Tsinghua University Initiative Scientific Research Programthe Thousand Young Talents Program of Chinathe financial support from China Postdoctoral Science Foundation (Grant 2014M562055)
文摘Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we perform molecular dynamics（MD） simulations to study the frictional behavior of a diamond tip sliding over a graphite surface. In contrast to the common wisdom, our MD results suggest that the energy barrier associated lateral sliding（known as energy corrugation） comes not only from interaction between the tip and the top layer of graphite but also from interactions among the deformed atomic layers of graphite. Due to the competition of these two subentries, friction on graphite can be tuned by controlling the relative adhesion of different interfaces.For relatively low tip-graphite adhesion, friction behaves normally and increases with increasing normal load. However,for relatively high tip-graphite adhesion, friction increases unusually with decreasing normal load leading to an effectively negative coefficient of friction, which is consistent with the recent experimental observations on chemically modified graphite. Our results provide a new insight into the physical origins of energy corrugation in atomic scale friction.
