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1 Wiadomości Chemiczne

1 1998

1 Kłonkowski A. M.

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w słowach kluczowych: szkła mieszane alkaliczne

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Ład w bezładzie, czyli kompleksy jonów metali przejściowych w szkłach i żelach tlenkowych

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Kłonkowski A. M.

tom [Z] 52, 1-2

57-85

The most basic difference between crystalline and non-crystalline solids is that a long range order (LORO) in the distribution of atoms (ions) or molecules exists only in crystalline materials [1]. This is indicated by diffraction patterns: the ideal crystal (the first extreme case) shows reflectants whose location and intensity obey three Laue conditions. The second extreme case is an ideally random structure. Scattering of radiation is impossible in the case of an ideally homogenous medium. Any real substance, including non-crystalline materials is inhomogenous regardless of its form or scale. Thus glasses can be thought of as assemblies of microcrystals (i.e. microcrystallites or paracrystals). Strain introduced due to lattice mismatch at grain boundaries, the presence of a disordered interfacial or matrix region, and defects such as dislocation, or stacking faults can be assumed to give rise to departures from periodicity at distances smaller than the average grain size [10]. In this sense glasses are interesting in the supramolecular science because they are intermediate objects in the way from random to organized matter [5]. The object of this article are such amorphous materials as inorganic oxide glasses with structural groups YO4, where Y = Si, P, and organically modified silicate gels. Among the studied glasses are ones of the type : R2O-SiO2 and R2O-Al2O3-SiO2, where R represents alkali atom (Li to Cs) [23, 25, 27], as well as M(II)O-P2O5, where M(II) is an alkaline earth atom (Mg to Ba) [28, 29, 32, 33]. Undoped glasses and those doped with copper (II) ions were investigated. These metal ions have played the role of probes. All the vitreous systems are classified according to their theoretical optical basicity [lambda] cal proposed by Duffy and Ingram [34]. Thanks to this method one can methodically observe and sensibly interpret changes of real measures of basicity as molar refractivity of oxide ions Ro (see Figs 9 and 10a), the so-called Imagawa's basicity (Fig.10b) and other physical and chemical properties of oxide glasses (Fig.11). The studied glasses are also classified according to their bond nature (Fig. 6)., taking into account their proximity to the onset of metallization [4]. Attention is also focused on the mixed alkali effect [22, 24]. A full understanding of the properties of colloids calls upon a wide range of physical and chemical ideas, while the multitude of colloidal systems presented to us in nature, and familiar in modern society, exhibits a daunting complexity. On the experimental side there is an ever-increasing emphasis on the application of modern physical techniques to colloidal problems. Colloid science is thus a truly interdisciplinary subject [3]. In the case of the xerogels there are described Cu(II) complexes existing on surface and in interior of the material [59-63]. Moreover, silica xerogels with immobilized supramolecular ligands show intensive luminescence (Fig. 17) which is effectively quenched by Cu(II) ions [64].