Chemical lattice incorporation

Precipitate particles grow in size because of the electrostatic attraction between charged ions on the surface of the precipitate and oppositely charged ions in solution. Ions common to the precipitate are chemically adsorbed, extending the crystal lattice. Other ions may be physically adsorbed and, unless displaced, are incorporated into the crystal lattice as a coprecipitated impurity. Physically adsorbed ions are less strongly attracted to the surface and can be displaced by chemically adsorbed ions. 

These conjugated polymers can be chemically and electrochemically reduced and reoxidized in a reversible manner. In all cases the charges on the polymer backbone must be compensated by ions from the reaction medium which are then incorporated into the polymer lattice. The rate of the doping process is dependent on the mobiHty of these charge compensating ions into and out of the polymer matrix. 

The ability of small concentrations of chemicals such as certain phosphates and polymers to retard relatively large amounts of crystal growth and eventual deposition by incorporation of the chemical into the crystal lattice. 

Based on the concept of mixed-framework lattices, we have reported a novel class of hybrid solids that were discovered via salt-inclusion synthesis [4—7]. These new compounds exhibit composite frameworks of covalent and ionic lattices made of transition-metal oxides and alkali and alkaline-earth metal halides, respectively [4]. It has been demonstrated that the covalent frameworks can be tailored by changing the size and concentration of the incorporated salt. The interaction at the interface of these two chemically dissimilar lattices varies depending upon the relative strength of covalent vs. ionic interaction of the corresponding components. In some cases, the weak interaction facilitates an easy... 

The incorporation of fluoride in place of hydroxyl groups is chemically straightforward [59,60] and, as we have seen, results in a substance of greater resistance to acid attack. This is partly due to the greater electronegativity of fluorine, which means that the electrostatic attraction between Ca + and F is greater than that between Ca + and OH. As a result, the fluoridated apatite lattice is more stable than hydroxyapatite [61-63]. It is also more crystalline [64]. 

Most of the successful rare earth activated phosphors comprise host lattices in which the host cation is also a rare earth. A principal reason for this relates to the optical inertness of La, Gd, Y, and Lu this is essential to avoid interference with activator emission spectra. Close chemical compatibility including amenability to substitutional Incorporation of rare earth activators are also essential features. Rare earth hosts such as oxides, oxysulfides, phosphates, vanadates and silicates also tend to be rugged materials compatible with high temperature tube processing operations and salvage. 

Fig. la. Atomic structure ofa two-dimensional nano-structured material. For the sake of clarity, the atoms in the centers of the crystals are indicated in black. The ones in the boundary core regions are represented by open circles. Both types of atoms are assumed to be chemically identical b Atomic arrangement in a two-dimensional glass (hard sphere model), c Atomic structure of a two-dimensional nanostructured material consisting Of elastically distorted crystallites. The distortion results from the incorporation of large solute atoms. In the vicinity of the large solute atoms, the lattice planes are curved as indicated in the crystallite on the lower left side. This is not so if all atoms have the same size as indicated in Fig. la [13]... 

Gray and Waddington [57,120] examined the physico-chemical properties of silver azide and state that its melting point is 300°C. On the basis of the latest opinion that the explosive decomposition of azides results from processes involving ions and electrons caused by imperfection and deficiencies in the crystal lattice (Jacobs and Tompkins [22]), the authors incorporated silver cyanide, Ag2(CN)2,... 

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