Latin lattice

Insertion (intercalation) compounds. Insertion compounds are defined as products of a reversible reaction of suitable crystalline host materials with guest molecules (ions). Guests are introduced into the host lattice, whose structure is virtually intact except for a possible increase of some lattice constants. This reaction is called topotactic. A special case of topotactic insertion is reaction with host crystals possessing stacked layered structure. In this case, we speak about intercalation (from the Latin verb intercalare, used originally for inserting an extra month, mensis intercalarius, into the calendar). 

For example, the book by Gomez and Gomez describes many possible designs such as the Latin square and the lattice designs. The former can handle simultaneously two known sources of variation among experimental units. Chapters deal with Sampling in experimental plots, and the Presentation of research results. ... 

A crystal of this sort, containing molecules that are not bonded to the framework of the crystal, is called a clathrate crystal (from the Latin word clai/iri, lattice). 

Clathrates are host-guest complexes in which a crystalline cage of the host compound holds the guest molecule by weak intermolecular forces. Often, the cavities of the guest molecule are formed by a network of hydrogen bonds between covalently bound compounds. Powell [126] names them clathrates from the Latin word clathratus , which means enclosed. It is interesting to note that the lattice structure of the host in the clathrate is not its normal crystalline form the former becomes thermodynamically more stable than the latter only by the formation of the host-guest complex. 

The type of adduct involved here was later termed a clathrate (from the Latin clathratus, meaning enclosed by the bars of a grating13) in which one material, in this case urea, forms a lattice which traps and holds a second type of molecule. Today this would be considered a subdivision of supramolecular chemistry.1314 The lattice formed has the shape and dimensions required to contain the molecule within the cage. In the case of urea, the cross section of the channel that urea can form is 5.5 A x 4.4 A, which is large enough to accommodate n-paraffins but insufficient for isoparaffins (6.0 A) or aromatics (5.9 A).15 Figure 9.6 illustrates the... 

There are certain substances formed by combining one stable compound with another or with an atomic or molecular element without the existence of any chemical bonds between the two components. This occurs when one of the compounds can crystallize in a very open structure containing cavities, holes or channels in which atoms or molecules of the other can be trapped. Those compounds in which the host lattice contains cavities like cages are the most important type they are called claihrate compounds, from the Latin... 

Since the work of Haiiy two centuries ago, every crystallographer knows that crystal lattices can never have a fivefold symmetry element. When recently Shecht-man actually synthesized them he got into trouble with his colleagues in physics but he also started a revolution in crystallography, which was by then as stationary as classical Latin. 

Smectic phases have also layers, but each layer has at least one more element of long-range order in addition to the director. There are several such phases, distinguished by capital Latin letters. Thus, in each smectic A phase the centers of molecules (in MLCs) or of LC sequences (in PLCs) lie on equidistant planes perpendicular to the director. In smectic B phases there are also such planes, but there is additionally a two-dimensional hexagonal lattice within each plane. There is no hexagonal structure in smectic C phases, while the director is tilted with respect to the plane normal (otherwise we would have another smectic A phase) an example is shown in Fig. 41.2(c). For a more detailed discussion of LC phases see for instance Chapter 6 in [18]. Phase transitions in MLCs are listed in books by Demus,... 

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