Solids mixing ordered

Solid mixed ionic-electronic conductors (MIECs) exhibit both ionic and electronic (electron-hole) conductivity. Naturally, in any material there are in principle nonzero electronic and ionic conductivities (a i, a,). It is customary to limit the use of the term MIEC to those materials in which a, and 0, 1 do not differ by more than two orders of magnitude. It is also customary to use the term MIEC if a, and Ogi are not too low (o, a i 10 S/cm). Obviously, there are no strict rules. There are processes where the minority carriers play an important role despite the fact that 0,70 1 exceeds those limits and a, aj,i< 10 S/cm. In MIECs, ion transport normally occurs via interstitial sites or by hopping into a vacant site or a more complex combination based on interstitial and vacant sites, and electronic (electron/hole) conductivity occurs via delocalized states in the conduction/valence band or via localized states by a thermally assisted hopping mechanism. With respect to their properties, MIECs have found wide applications in solid oxide fuel cells, batteries, smart windows, selective membranes, sensors, catalysis, and so on. 

Even when complete miscibility is possible in the solid state, ordered structures will be favored at suitable compositions if the atoms have different sizes. For example copper atoms are smaller than gold atoms (radii 127.8 and 144.2 pm) copper and gold form mixed crystals of any composition, but ordered alloys are formed with the compositions AuCu and AuCu3 (Fig. 15.1). The degree of order is temperature dependent with increasing temperatures the order decreases continuously. Therefore, there is no phase transition with a well-defined transition temperature. This can be seen in the temperature dependence of the specific heat (Fig. 15.2). Because of the form of the curve, this kind of order-disorder transformation is also called a A type transformation it is observed in many solid-state transformations. 

Nanosized ZnO particles are prepared by hydrolysis-condensation at moderate temperature (from 20 to 70°C) [27-29] of zinc-acetate precursors [30] in ethanolic medium. Besides the determination of local order around Zn and of the particle sizes during the nanosized ZnO preparation, the motivation of the combined investigation was also to clarify the occurrence of a Zn-based hydroxy double salt phase, Zn5(0H)8(0C0CH3)2.2H20 (labeled hereafter Zn-HDS) observed as final solid mixed with ZnO and zinc acetate phases [29]. In particular, we were interested in determining whether the formation of the Zn-HDS phase was concomitant to the ZnO formation or arose from the reaction of ZnO with zinc acetate precursors during ageing of the colloidal suspension before extraction of solids. 

Multi-phase mixing is often seen in industries. In general, the distribution of not only the dispersed phase but also the continuous phase depends on the local position in the equipment in the case of a multi-phase operation such as gas-liquid mixing system, liquid-liquid mixing system, solid-liquid mixing system, and gas-liquid-solid mixing system. In order to evaluate the mixing state in such systems, both the dispersed phase and continuous phase should be considered. 

One of the remarkable features of the FFB is its very high heat transfer rate. Because of extensive solids mixing in the FFB, the heat transfer rate between particles is several orders of magnitude higher than that of silver by conductive heat transfer. The high heat capacity and thermal conductivity... 

A new chapter on membrane separations has been added, and the order of the chapters on multicomponent distillation, extraction, drying, and crystallization has been made more logical. The discussion of particulate solids has been shortened and two former chapters on properties and handling of solids and of solids mixing have been combined into one. New material has been added on flow measurement, dispersion operations, supercritical extraction, pressure-swing adsorption, crystallization techniques, crossflow filtration, sedimentation, and many other topics. The treatment of dimensional analysis has been condensed and moved from the appendixes to Chapter 1. 

L. T. Fan et al.. Powder Technology, 68, 195-196 (1991)]. However, Egermann [L. T. Fan, Y. Chen, and F. S. Lai, Recent Developments in Solids Mixing, Powder Technology 61, 255-287 (1990)] points to the fact that one should only use ordered mixing to describe the condition and not the mixing of fine particles using powerful interparticle forces. 

Dialkoxy-PPEs are very similar to the dialkyl-PPEs, but considerably less stable. While dialkyl-PPEs can be melted without decomposition, dialkoxy-PPEs tend to degrade above 120°C and no thermotropic phases have been reported, however, nematic lyotropic preparations [58] were observed. The solid state ordering of dialkoxy-PPEs is similar to that of the dialkyl-PPEs [59]. Dialkoxy-PPEs are more electron rich and show a smaller bandgap than dialkyl-PPEs, i.e., their absorption and emission are redshifted with respect to that of the dialkyl-PPEs. Mixed systems have been reported by West, but seem to show properties that are more like those of dialkoxy-PPEs than those of the dialkyl-PPEs [10]. 

A10 kWjij continuous reactor of interconnected fluidized beds has been discussed in Ref. [55] for CLC with biomass (Figure 5.12). The prototype is composed of a fast fluidized bed as air reactor, a cyclone and a spout-fluid bed as fuel reactor. In this case, the spout-fluid type reactor is adopted as fuel reactor in order to have a strong solid mixing between the biomass and OC particles and a long residence time. The spout-fluid reactor is designed to have two difl erent compartments. In the first part, the reaction chamber is located where the OC and the biomass are combined to produce exhaust gas and solid species (metal oxide and unconverted fuel), while the second part contains the inner seal that is located at the top and it is used to allow solids movement to the air reactor. The fuel reactor is fluidized by using exhaust gas recirculation (Table 5.2). 

The thermodynamic behaviour of polymer solutions has been the subject of extensive study, partly because of the importance of surface coatings such as lacquers and paints, and partly because it is essential to understand the behaviour of polymers in solution in order to quantitatively characterize the polymers and copolymers. Furthermore, it is also not possible to understand the behaviour of polymer-polymer systems (blends and alloys) without some understanding of polymer-solvent systems. There is a close relationship between the way in which amorphous solids mix and the behaviour of polymers in solution polymer solutions are much more amenable to experimental measurements. 

Formally, the technical procedure of the immersion method described in Section III.B can be applied to measure the relative enthalpy of immersion in a single step instead of in two steps. In this case, a suspension of the adsorbent in the solvent is sealed in the bulb and thermally equilibrated with the surrounding solution in the calorimeter vessel [22]. When the ampoule is broken, the solution mixes with the solvent and the adsorption proceeds until a new equilibrium state is attained. The experiment is then repeated in the absence of the solid in order to determine 2con + the heat attributable to the breaking of the ampoule plus the enthalpy of dilution of the solution in the solvent. The relative enthalpy of immersion is calculated as... 

Numerous research problems of practical and industrial importance and of theoretical and academic interest await solution in the preparation, characterization and application of ordered mixtures and composition-stable mixtures. Scant attention is paid here to these subjects because they are regarded as being outside the scope of bulk-solids mixing in the conventional sense, which usually is concerned with mixing and blending of free-flowing particles and powder in relatively large quantities. 

Table 2 also shows that the number of ideal mixers is so large that solids mixing in axial direction can be neglected. It appears that the number of mixers is of the same order of magnitude as the average number of times a particle rolls down the surface of the solids bed. 

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