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Intr"ducti"nNano-size particles of noble metals (Ag, Au, Pt) are today a subject of thorough attention of scientific researchers and of technologists, because these particles reveal the wide range of physical features, absent in the case of bulk media. Size-controlled optical properties of Ag-nanoparticles open good prospects for potential technological applications -such as diffraction elements, optical filters, nanoplasmonic devices, bi-sensors, and nonlinear media. Silver nanoparticles can be produced in various media -in water solutions, in polymers, in glasses, and in crystalline media. For instance, the long period in photographic imaging technique was based on the photoinduced production of Ag nanoclusters in the crystals of AgHal (the latent image). At the same time one can say that the inorganic glasses are the unique matrix for silver nanoparticles formation. The wide temperature range of glass viscosity growth provides the possibility to control over the Ag nanoparticles size within the wide range by means of modifying the temperature and duration of thermal processing. In the fact, only such kind of matrix makes it possible to control and investigate all the stages of Ag nanoparticles formation, including the starting stage. Glass coloring by introduction of the metallic Ag nanoclusters is one of the ancient methods, known by humanity [1]. The mechanisms, leading to nucleation and growth of such nanoclusters, are the scientific and technology problem, important both for colored glass production and for all other potential applications of glass with silver nanoparticles [2][3][4][5]. The researches on silver nanoclusters formation comprise numerous technical approaches. Especially interesting are the methods, based on the use of ionizing radiation, are especially interesting due to their ability provide either local irradiation or to irradiate the whole volume of the glass. In this case it is comparatively simple to provide the control over concentration and average size of metallic nanoclusters. For instance, the controlled photon irradiation is used for production of photosensitive [6], polychrome [м] and photo-thermorefractive [н] glasses. Very often all these types of glasses are called the photosensitive one (PS). Further within this chapter we shall use this word. 10www.intechopen.com

The precipitation of nanosized crystals CuBr and CuCl in potassium aluminoborate glasses con taining additives of jointly introduced Cu and Br, as well as Cu and Cl, respectively, has been studied by the methods of small angle X ray scattering (SAXS) and X ray powder diffraction (XRPD) analysis. It has been found that, upon thermal treatments at temperatures close to the glass transition temperature T g , halide phases precipitate in the form of liquid drops containing CuBr and KBr or CuCl and KCl. The presence of nanocrystals CuBr or CuCl, respectively, has been established in the samples at room temperature by the XRPD method. Liquidus, solidus, and crystallization onset temperatures in the regions of precipitated halide phases in heat treated glass samples have been determined from the temperature dependences of SAXS inten sity. The liquid released upon the heat treatment inside a matrix of potassium aluminoborate glass remains in the state of a supercooled liquid at temperatures essentially below the solidus temperature. At the drop sizes of the order of 10 nm, crystallization processes in them start at temperatures of 40-85°C.

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