الفهرس 
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Abstract
This work is aimed to use the advantages of 29Si and 31P NMR as a sensitive powerful tool to give specific correlation between structure and properties of modified silicate glasses containing CrF2. We devoted our trials to study the microstructural properties of these glasses in terms of glass composition. The present results showed that the substitution of SiO2 by chromium fluoride brings changes in the structure and properties be havior of the resulting glass. Modern solid-state nuclear magnetic resonance (NMR) methodologies are applied to investigate two -5/2 nuclei (29Si and 31P) as well half spin 29Si nuclei in different coordination environments. High resolution (12.3T) MAS NMR is applied in order to characterize the material structure which may be depended on the electric field gradient (EFG) and nuclear magnetic shielding of these nuclei. The advantages of using high MAS NMR technique were appeared in detecting 29Si and 31P spectra directly at ambient temperatures. As a result, successful investigations of the different silicon and phosphorus sites in more in glass complex system containing silicate and chromium fluoride. In all investigated glasses the high – field 29Si and 31P NMR experiments are employed to determine the composition and number of silicate glasses containing chromium fluoride. In this thesis, we have followed the structure changes in the network of silicate glasses containing chromium fluoride by using additional structural techniques. XRD and EDP spectroscopy are carried out differentiate between range ordered species upon CrF2 additions. TEM and SEM were used to study the morphological changes as a result of changing glass composition. In general, SEM, X-ray diffraction, EDX pattern and FTIR spectra of chromium fluoride containing glasses revealed nanostructure of silicate species. The type of crystalline silicate phases are found to have some direct effects on some material properties.