الفهرس 
Aim of the WorkOnly 14 pages are availabe for public view
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Abstract
In the present work, binary phosphate glasses of general formula xPbO.(100˗x)P2O5 and xCeO2.(100˗x)P2O5 over compositional range from x= 40 to 70 mol% and x=20 to 40 mol% respectively have been investigated. In addition, glasses in ternary system of composition ; xCeO2.(50˗x)PbO˗50P2O5 are also studied over compositional range from x= 0 to 40 mol% to shed some light on structure role of CeO2 in phosphate network. CeO2 is added at the expense of PbO for the development of some physical properties for the phosphate glasses. These glasses were successfully prepared by using conventional melt quenching technique. This study presents structural evaluation for lead-phosphate glasses, which were either amorphous or crystallized. The results have indicated that, there is a clear difference in mechanism of changing of material structure, depending on whether the glass was amorphous or contained crystalline phases. Based on the data extracted from X-ray diffraction (XRD), electron diffraction (EDP), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectra (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy, glasses contain ≤ 55 mol% PbO are initially amorphous and contain relatively intermediate amounts of depolymerized (Qn) phosphate units. The structure of the studied ternary cerium lead phosphate glasses was found to depend on structural factor CeO2/PbO. The related low changes in the region ≤ 15 mol% were referred to condition which forces both CeO2 and PbO to be participated in the phosphate matrix as glass modifiers. At higher cerium oxide concentration > 15 mol%, tetrahedral CeO4 units as strong former species was induced with increase in CeO2/PbO ratio as indicated according the FT-IR and 31P NMR results. These features were correlated to the higher field strength of Ce as compared to Pb cations. On the other ward, XRD features didn’t reveal any crystallizations. But EDP, TEM and SEM measurements have confirmed the presence of some crystalline phases. SEM and TEM showed agglomerates consist of clusters in micro scale separated from the main amorphous phase. Formation of such type of clusters is a confirmation on the change of the structure nature of the studied glasses and properties, since the hardness number of the studied materials is highly enhanced. The formation of Ce-O-P linkages increases the ability of the material to withstand more stress due to indentation process. In glass of lower CeO2 content (≤15 mol%), photoluminescence emission increased due to increase of transition by Ce3+ ions, responsible for (4f→5d transition) to cause reduction of Ce4+ to Ce3+ ions while referred to increasing NBO in the glass network. In glasses of higher CeO2 content (>15 mol %), photoluminescence emission remarkably decreased due to oxidation of Ce3+ to Ce4+ ions, which is charges transfer between Ce4+ and NBO atoms. In a specific regard, the purpose of this study was to confirm the role of cerium oxide, which was suggested to convert commercial glass into magnetic glass for technical and scientific applications. The magnetization was found to depend on the CeO2 concentration, regardless of whether it was added as a dopant or had a high content. Hysteresis loop curves for samples in the studied system at room temperature confirmed that the mixed superparamagnetic and paramagnetic behavior is the dominant for binary cerium phosphate glasses. While ferrimagnetic features have been observed in cerium lead phosphate glasses. In this regard, the magnetic behavior of the glasses is found to be affected by presence of cerium phosphate clustered phases, which related to Ce4+ and Ce3+ concentration.In the field of applications, cerium phosphate precipitated phases are usually applied in glasses which be used as biocompatible material. In addition, the mixed lead cerium phosphate phases are used as shielded glasses for irradiations and UV–ionic radiations. Moreover, cerium oxide can be used in glass decorations due to color changes. The network which is formed from cerium phosphate amorphous and lead phosphate crystals is a base matrix for transparent glass ceramics which can be used in sun glasses for UV protections. Lead phosphate glass involves a ferro elastic phase Pb3(PO4)2 regarded as orthophosphate crystalline phases can be used as new functional alloys for various dental and medical applications.