Intercalation compounds electrical properties

Five aspects of the preparation of solids can be distinguished (i) preparation of a series of compounds in order to investigate a specific property, as exemplified by a series of perovskite oxides to examine their electrical properties or by a series of spinel ferrites to screen their magnetic properties (ii) preparation of unknown members of a structurally related class of solids to extend (or extrapolate) structure-property relations, as exemplified by the synthesis of layered chalcogenides and their intercalates or derivatives of TTF-TCNQ to study their superconductivity (iii) synthesis of a new class of compounds (e.g. sialons, (Si, Al)3(0, N)4, or doped polyacetylenes), with novel structural properties (iv) preparation of known solids of prescribed specifications (crystallinity, shape, purity, etc.) as in the case of crystals of Si, III-V compounds and... 

Titanium disulfide, like the disulfides of Zr, Hf, V, Nb, and Ta, has a layer structure two adjacent close-packed layers of S atoms have Ti atoms in octahedral interstices. These sandwiches are then stacked so that there are adjacent layers of S atoms. Lewis bases such as aliphatic amines can be intercalated between these adjacent sulfur layers similar intercalation compounds can be made with M and MSe2 compounds for M = Ti, Zr, Hf, V, Nb, and Ta. Many of these have potentially useful electrical properties, including use as cathode material for lithium batteries, and superconductivity, and may be compared with the intercalation compounds of... 

The sulfides have been studied much less than the oxides, but it is clear that many similarities exist. Like the oxides, a number of stable phases exist and nonstoichiometry is prevalent. The most important sulfide is TiS2, which has the Cdl2 layer structure, in which the Ti atoms occupy octahedral sites between alternate layers of close-packed sulfur atoms. The adjacent sulfur layers are able to intercalate Lewis bases such as aliphatic amines. Similar intercalation compounds can be made with MS2 and MSe2 compounds (M = Ti, Zr, Hf, V, Nb, Ta). Many of these compounds exhibit useful electrical properties including superconductivity see Superconductivity). 

The layered compounds AMO2 where M is a transition metal and A an alkali metal, Cu or Ag have attracted interest because of their electrical properties. LiCo02 is used in rechargeable lithium ion batteries and Na, Co02 is metallic except at x = 0.5 and for values of x of about 0.35 becomes superconducting in the presence of intercalated water. Li et and Xu and Zeng have studied Nao.5Co02. A... 

The formation of a nanostructure in the intercalation compound not only enables the expansion and contraction of the host material during guest insertion and extraction, but also increases the surface to volume ratio. Recently, V2O5 synthesis focussed on the manufacture of nanostmctured or mesoporous scaffolds with the aim to improve their lithium ion intercalation properties, which are limited by an inherently low diffusion coefficient D < 10 cm s ) and a moderate electrical conductivity ([Pg.91]

Some crystalline compounds of the type MjPjSg (e.g. M = Mn, Zn, Fe, Ni, Cd and their selenium analogues) are lamellar semiconductors with interesting electric and magnetic properties which are consequent upon the structural arrangement (MPS3 structure-type) (Figure 9.19). These properties are profoundly modified on the formation of intercalation compounds with small quantities of amines, Li+ cations, dibenzenechromium and so forth [24-27]. 

In this chapter, we present the physical properties of cathodes materials and verify the applicability of the rigid-band model for intercalation compounds with a layered structure namely transition-metal chalcogenides MX2 (M = Ti, Ta, Mo, W X = S, Se) and oxides LLWO2 (M = Co, Ni) as well. Electrical and optical properties are investigated. For some materials, we observe different degrees of irreversibility in the intercalation process and lattice evolution to the complete destruction of the host. Since the purpose here is the study of the materials in the framework of... 

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