Thesis (PH.D.) - Cairo University - Faculty Of Science - Department Of Biophysics

The thesis comprises the preparation of some silicate and phosphate glass - ceramics and the characterization of the prepared samples to investigate their structureAlso , in vitro and in vivo tests for the prepared samples were carried out to investigate their bioactivityThe basic silicate glasses were of the system SiO2 - CaO - Na2O - P2O5 , where the effect of addition of MgO and / or TiO2 on the bioactivity was investigatedThe basic phosphate glasses were of the system P2O5 - CaO - Na2O , where the effect of addition of TiO2 on the bioactivity was investigated The parent glasses were prepared from chemically pure raw materialsMelting of the weighed batches was carried out in an electric furnace using platinum crucibles at about 1450 oC for the silicate glasses , and using porcelain crucibles at about 1150 oC for phosphate glassesThe homogenized melts were poured and annealed in a regulated muffle furnace at 470 oC for the silicate glasses , and at 350 oC for the phosphate glasses The parent glasses were converted to their corresponding glass - ceramics by controlled heat - treatment regime using the thermal analysis data of the samplesThe prepared glass - ceramic samples were characterized using X - ray diffraction measurements to identify the crystalline phases present in the samplesAlso , the infrared absorption spectroscopy and Raman Spectroscopy were used to investigate the structure of samplesScanning electron microscope measurements were carried out to investigate the texture of the surface of the samplesFor the silicate glass - ceramic samples , sodium calcium silicate was identified as the main crystalline phaseBy the addition of MgO or TiO2 , a second minor phase was formed and was identified as calcium phosphateThe silicate glass - ceramic samples showed almost complete crystallization and the infrared absorption spectra revealed the presence of the characteristic peaks of the SiO4 groups inside the crystalline phasesFor the phosphate glass - ceramic samples , the calcium pyrophosphate was identified as the main crystalline phase in all the samplesThe base sample without addition of TiO2 showed also the presence of sodium metaphosphate , which was present in all the samples with considerable amounts , and other minor phases (calcium metaphosphate , sodium pyrophosphate , sodium calcium metaphosphate) By the addition of TiO2 , the crystalline phase sodium calcium phosphate was disappeared and the sodium metaphosphate was decreased except in sample P5 with TiO2 = 2 mol In hundered persent where the amount of sodium metaphosphate was still high as in the base sampleAlso , a new crystalline phase was formed , which can be identified as sodium titanium phosphate

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