Novel Layered Materials Non Phosphates

Figure 1 Schematic classification of layered solids (d = inter-layer distance).

planes. Graphite is however rigid against longitudinal in-plane distortions.

2. Type II layered materials, such as dichalcogenides and lamellar oxyhalides, have layers composed of a few (usually three) distinct planes of strongly bonded atoms held together by van der Waals forces.

3. Type III layered materials have layers made up of dense (up to seven) assemblies of strongly bonded atoms. The layers may be charged in which case the interlayer forces are ionic resulting in layered structures, such as silicate clays and layer double hydroxides, which are quite rigid to interlayer distortion or expansion.

Figure 1 gives a schematic illustration of the three classes of layered materials.

In all cases the intralayer forces are much stronger than the interlayer forces and therefore guest species can be inserted into the interlayer region between the host layers without any change to the layers themselves. This attractive feature of layered materials has been extensively exploited. Indeed, the bidimensional character of many layered materials can be gradually modified by intercalation, grafting, or pillaring with a variety of guest species to yield new classes of novel layered materials. Type I intercalation materials, such as those of graphite, form stages in which n-multi-layers of the host are separated by monolayers of guest intercalant to form expanded «-stage materials. Type II materials are able to accept guest species into random interlayer sites and may ultimately form a saturated stage-1 expanded material at sufficient guest species concentrations. In contrast type III materials always form intercalation compounds with a stage 1 stacking sequence in which the host layers are separated by one or more layers of the guest species. Novel layered materials that have found use in separation processes are mainly (intercalated or otherwise modified) type III materials and this paper is therefore devoted to such materials with only a brief mention of type I and type II intercalated materials (using graphite and dichalcogenides as examples) given below.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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