Arrhenius behavior mobility

Na+ ions are highly mobile compared to the glass-forming components and possess a diffusivity which follows Arrhenius behavior [21, 26, 29, 31, 33]. Furthermore, the activation energy for diffusion decreases markedly (and the diffusivity increases correspondingly) as the modifier concentration is increased, as in Fig. 10.8. The... 

The experimentally determined material (PSFLCs and FLCs) viscosity obeys typical Arrhenius behavior (6.19) with increasing temperature. This means with increase in temperature ye decreases in a typical exponential manner for both PSFLCs and FLCs. We also observe that addition of polymer network increases the rotational viscosity in case of PSFLCs compared to that of pure FLCs (Fig. 6.2). This is a direct consequence of (6.19) and remarkably, experimental observations made by Pal Majumder et al. (1994) strongly supports our stand. Increase in yg for PSFLCs implies the incorporation of polymer network which reduces the rotational mobility of the molecular director and otherwise it has large rotational freedom in case of neat FLCs. 

It is generally assumed that temperature dependence of % follows Arrhenius behavior, and then the activation energy for Li ion mobility is determined by... 

The electrical response observed in conventional polymer is usually interpreted by non-Arrhenius behavior. The temperature dependence of DC conductivity measured from the polymer electrolytes is the hallmark of ionic motion being coupled with the host matrix. The temperature dependence of the conductivity exhibits an apparent activation energy that increases as temperature decreases. This behavior is most commonly described by the empirical VTF equation, which was first developed to describe the viscosity of supercooled liquids. However, there is a different class of polymer electrolyte, discussed and first reported by Angell, suggesting that the ionic conductivity is not coupled to the segmental motion of the polymer chain, that is, in which the ions move independently of the viscous flow. ° Based on this approach, Souza recently reported a new class of DHP (synthesis route discussed above), in which the ion mobility presented an Arrhenius behavior of the conductivity as a function of temperature, suggesting that the ion motion is decoupled from the polymer segmental motion for temperatures above Tg (about... 

The relationship between the ionic conductivity oi and the temperature T can either be derived from the diffusivity D or the mobility u assuming Arrhenius-type behavior ... 

Trillo et al. (47,137) have reported compensation behavior in oxide-catalyzed decomposition of formic acid and the Arrhenius parameters for the same reactions on cobalt and nickel metals are close to the same line, Table V, K. Since the values of E for the dehydration of this reactant on titania and on chromia were not influenced by doping or sintering, it was concluded (47) that the rate-limiting step here was not controlled by the semiconducting properties of the oxide. In contrast, the compensation effect found for the dehydrogenation reaction was ascribed to a dependence of the Arrhenius parameters on the ease of transfer of the electrons to the solid. The possibility that the compensation behavior arises through changes in the mobility of surface intermediates is also mentioned (137). 

Manganese nodules often exhibit onionskin layering of Feflll) oxides (Arrhenius, 1963). The surfaces of many soil Mn concretions, composed predominantly of birnessite, are coated with ferruginous and siliceous material (Taylor et al., 1964). The intermixing or coating of various chemical species with/on Mn oxides could substantially alter their redox and sorption/desorption behavior and profoundly affect the mobility and fate of many nutrients and pollutants in natural environments. However, there is only limited information in the literature on the subject. Oscarson et al. (1981b) hypothesized that a coating of carbonates on Mn oxides was responsible for a retardation in the rate of oxidation of As(III) by some freshwater lake sediments. 

The mobility increases with temperature this behavior is the opposite of what is observed in crystals, and provides a clear proof that conduction occurs through thermally assisted hops. Whereas a simple Arrhenius law for the zero-field mobility In (ji0) oc 1 /T can be used to fit the data in many systems [57], ithas been shown that a dependence of the type In (fi0) oc 1 /T2 is more adequate [60], although its physical interpretation can hide both disorder or polaron-related effects [55],... 

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