الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
This thesis presents new information on different glasses in the system xCeO2(1-x)B2O3, where x changed from 20 to 60 mol%. It is aimed, in this work, to shed more light on the effect of glass composition and irradiation on microstructure of the investigated glasses. Effect of thermal treatments on structural properties of irradiated glasses is also studied. Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) equipped by electron diffraction apparatus (EDP), X-Ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray analyzer (EDS) are the tools used to characterize the glasses. It is well known that addition of modifier oxides to B2O3 can directly convert BO3 triangle to BO4 tetrahedral units. On the other hand, high modification level can produce non bridging bonds in borate network. But addition of CeO2 to B2O3 found to have a different structural role, since non bridging bond cannot be formed even at extra high CeO2 concentrations. In such situation, CeO2 is consumed in forming both tetrahedral cerium (CeO4) and tetrahedral boron (BO4). In addition, cluster species from Ce ions are formed in high cerium glasses. This means that the structure role that played by the convential modifier oxide such as alkali is totally differed from that of CeO2 in modifications the network of B2O3. Only CeO4, BO4, and different types of clusters from ceria are the structure species that could be identified by the different applied techniques. It is concluded that at low CeO2 content (≤ 40 mol%) cerium can mainly play the role of glass former. Glass modifier and former would be considered the structural role played be CeO2 in higher cerium glass. Depending on glass composition, it is found that radiation can promote the conversion rate of BO3 units to BO4 groups especially in the low CeO2 containing borate network. As a result of irradiation, the major part of CeO2 is preferred to inter the glass as a modifier i.e., transform BO3 units to BO4 groups in low ceria content and transform BO4 units to another units containing (NBOs) at higher levels of the modifier. The formation of (NBOs) is discussed on basis of formation of defects or disordered structure which could be evidenced by XRD patterns of all irradiated glasses. In as obtained glasses, formation of non-bridging oxygen is not considered even at relatively high concentration of CeO2. Changes in boron coordination, ordering structures, and phase transitions of the irradiated borate materials are the main parameters which were discussed in terms of effects produced by the ionizing radiation. The final discussed item is the effect of thermal heat treatment on the network structure of irradiated borate glasses. In this regard, it is concluded that heat treatment was found to have some effects toward partial or complete removal of radiation effects. Thermal heat treatment process was found to have prefund effect on the changes produced by the radiation. Some structural defects are partially and / or totally released by the influence of heat treatment. It is revealed that in the case of low CeO2-irradiated glasses (≤ 50 mol%), the concentration of irradiation – induced defects cannot be released by the heat treatments. On the other hand, the induced defects was found to be released and removed by treating the glasses of higher CeO2 contents (glass contains 55, and 60 mol%).