Solid-state reactions metals

Manganaies IV), manganites. Mixed-metal oxides containing Mn(IV). Prepared by solid state reactions. 

The Pb02/PbOx border slowly penetrates into the metal, but only at a very slow rate as a solid-state reaction. Cracks are formed when the oxide layer exceeds a given thickness, on account of the growth in volume when lead becomes converted into lead dioxide (Table 7). Underneath the cracks the corrosion process starts again and again. As a whole, the corrosion proceeds at a fairly constant rate. It never comes to a standstill, and a continually flowing anodic current, the corrosion current is required to re-establish the corrosion layer. 

With boron and an appropriate amount of some sort of alkaline metal halide present in the starting materials for the solid-state reactions, then we obtain zirconium cluster materials belonging to the 6-14 family. Single-crystal X-ray data of products from iodine-rich reactions were used to determine the crystal structures of Na[(Zr6B)Cl3.87(5)lio.i3], and Cs[(Zr6B)Cl2.i6(5)lii.84] [21]. Both phases... 

Mixed Chloride-Iodide Zirconium Cluster Phases with a 6 18 Metal Halide Ratio -Products from Solid-state Reactions... 

If iron metal would oxidize to form a homogenous oxide layer without flaking off, draw a diagram showing the reaction conditions, the phase boundary formed and the diffusion conditions likely to prevail in the solid state reaction. 

In addition to metals, other substances that are solids and have at least some electronic conductivity can be used as reacting electrodes. During reaction, such a solid is converted to the solid phase of another substance (this is called a solid-state reaction), or soluble reaction products are formed. Reactions involving nomnetaUic solids occur primarily in batteries, where various oxides (MnOj, PbOj, NiOOH, Ag20, and others) and insoluble salts (PbS04, AgCl, and others) are widely used as electrode materials. These compounds are converted in an electrochemical reaction to the metal or to compounds of the metal in a different oxidation state. 

Solid state reactions are also very common in producing oxide materials and are based on thermal treatment of solid oxides, hydroxides and metal salts (carbonates, oxalates, nitrates, sulphates, acetates, etc.) which decompose and react forming target products and evolving gaseous products. Solid-state chemistry states that, like in the case of precipitation, powder characteristics depend on the speed of the nucleation of particles and their growth however, these processes in solids are much slower than in liquids. 

Common routes for the synthesis of selenates and tellurates(IV and VI) are the reactions of metal oxides or carbonates with the repsective acids (see Section 4). The disadvantage of this procedure is, that one usually obtains hydrates or, at higher acid concentrations, acidic compounds. Because the oxides E03 and E02 (E=Se, Te) are solids under ambient conditions, solid-state reactions with the respective metal oxides are an alternative route to prepare the anhydrous compounds. 

YDC has been prepared by various methods, including solid-state reaction, coprecipitation, glycine-nitrate process and metal organic chemical vapor deposition (MOCVD). Table 1.4 shows that the properties depend on the preparation method [118,119,127,129,130], Zha et al. [129] have studied the influence of sintering... 

Jiang, Y. Decker, S. Mohs, C. Klabunde, K.J. Catalytic solid state reactions on the surface of nanoscale metal oxide particles. J. Catal. 1998,180,24-35. 

Care has to be taken when extrapolating kinetic parameters measured under melt-phase conditions for describing the solid-state reaction. The available kinetic data are not free from mass-transfer influences and the effects of proton and metal catalysis are not thoroughly separated. Therefore, the adaptation of kinetic parameters is often carried out by fixing the activation energies and adjusting the pre-exponential factors to the experimental data. 

With the metals of the 4th group (Ti, Zr, Hf), solid solution phases are observed which, for the limiting composition 1 2, have the CaF2-type structure and (through solid state reactions) the tI6-ThH2-type. 

Arc-melting Well mixed (in some cases partially pre-reacted) compacts of carbon and the metal may be reacted by melting arc-melting may be especially suitable. An advantage of melting in comparison with solid-state reactions may be related to the fact that arc-melted pieces have a smooth surface less susceptible to contamination. This method was found especially effective for refining and for the preparation of solid solutions mainly of the 4th and 5th carbides groups. 

R.B. Schwarz, W.L. Johnson, Formation of amorphous alloy by solid-state reaction of the pure polycrystaUine metals, Phys. Rev. Lett. 51(5) (1983) 415 18. 

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