الفهرس 
List of ContentsOnly 14 pages are availabe for public view
 |  | from | 147 |  |  |
| | | from | 147 | | |
Abstract
Different glass samples in the CaO-Na2O-CeO2-B2O3-P2O5 system have been prepared and evaluated. Their structure has been recognized. Understanding and interpreting data based on structural changes in the studied glasses after the addition of cerium oxide was of particular interest. This could be because many commercial glasses containing some of this oxide (CeO2) are suitable for technological applications in a variety of fields. A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and 31P NMR spectroscopy. The microstructures of samples contain < 1 mol% CeO2 are amorphous in nature. More addition of CeO2 transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM).FTIR analysis combined with NMR results can be used to calculate the fraction of four coordinated cerium atoms within the structure. The obtained results have revealed that the addition of more than 0.8 mol% CeO2 can promote nucleation and crystallization routes that are combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO2 showed no tendency to crystallization. The crystals of CeO2 containing glasses were spheroid like morphology that was assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species in three-dimension plays better compatibility and bioactivity behavior than that of the other types of morphology. This is may because the spherical shape has a higher surface area than that of the needle-like morphology. Accumulation and aggregation of small-sized spheres from cerium borate phases played the role of enhancing the hardness of the studied materials. In this study, we also would like to know that if cerium oxide could be used to convert amorphous glass into crystalline glass-ceramics suitable for medical applications. In this regard, glass ionomer cement (GIC) has been developed as an acid-base cement type for orthopedic and orthodontic applications. As a result, the focus of this work was on investigating the cement properties of the investigated glasses. The concentration of CeO2 was revealed to be a factor in the formation of cemented cerium borate glasses.