- 學位論文
Na2O-CaO-P2O5-SiO2系生物活性玻璃之彈性性質與結構：鈣/磷比值的效應及與Na2O-CaO-SiO2系玻璃的比較
Elastic properties and structure of the Na2O-CaO-P2O5-SiO2 bioactive glasses: effects of Ca/P ratio and a comparison with the Na2O-CaO-SiO2 glasses
摘要
本研究利用拉曼(Raman)及布里安(Brillouin)散射探討鈣/磷比值對Na2O-CaO-P2O5-SiO2生物活性玻璃之彈性性質及結構的影響，以瞭解鈣與磷改變對玻璃彈性及結構性質的可能效應，我們同時比較CaO/Na2O對不含磷之Na2O-CaO-SiO2 系玻璃的效應。從實驗結果得知，陽離子(Ca2+)扮演著網路改質劑(modifier)的角色，進入矽酸鹽網路空隙，使密度提高；當玻璃之CaO/P2O5之莫耳比增加時，此四元玻璃的體積模數(bulk modulus，B)、剪力模數(shear modulus)、楊氏模數(Young’s modulus，E)均提高，並伴隨著Q0、Q1、Q2的增多及Q3、Q4矽酸鹽結構單元的減少。另一方面，CaO/Na2O莫耳比的增加也同樣導致Na2O-CaO-SiO2系玻璃彈性模數的升高，甚至於結晶後之Na2O-CaO-SiO2系晶體的彈性也隨CaO/Na2O增大而提高。揆其因，在玻璃方面之E、K與G升高主要與Ca2+增加導致內聚力較大，在晶體方面除了結構不同外，也可能是Ca-O鍵能比Na-O高所致。比較含磷及不含磷玻璃及其結晶相，可發現含磷者之彈性模數均較低；對玻璃而言，磷的加入可能引起相分離降低Ca2+在內聚力的貢獻及可能P-O-Si鏈比Si-O-Si弱；對晶體而言，則可能涉及因P5+取代Si4+所造成的晶體結構扭曲。最後，本研究所探討之玻璃及結晶相的楊氏模數均在可用生醫玻璃及陶瓷的範圍內，故我們可藉改變CaO/P2O5比值或CaO/ Na2O相對值及熱處理以得到適用之移植玻璃及玻璃陶瓷。
並列摘要
The effects of CaO/P2O5 molar ratio on the elastic properties and structure of the Na2O-CaO-P2O5-SiO2 bioactive glasses and have been studied using both Brillouin and Raman spectroscopy. The effect of CaO/Na2O molar ratio on the Na2O-CaO-SiO2 glasses was also examined. It was found that the density of glass in both series increases with increasing the concentration of CaO. This case indicates that Ca2+ ions act as network modifiers in these glasses. When the concentration of CaO increases, all the three elastic moduli shear (G), bulk (K), and Young’s (E) moduli of the two series of glasses increase although it accompanies an increase in the abundance of Q0, Q1, and Q2 species and a drop in the abundance of Q3, and Q4 species. The strengthening due to depolymerization of the silicate network can be attributed to an increase in cohesion of glasses caused by the addition of CaO. An additional crystallization experiment on the Na2O-CaO-SiO2 glasses has revealed that the elastic moduli of the crystalline phases also increase with the increase of CaO/Na2O molar ratio. This case has been correlated to that Ca-O bond is stronger than Na-O bond at the same coordination except for the difference in crystal structure. A further study on the P-bearing (45S5.2 glass, i.e., BG2) and Na2O.CaO.2SiO2 (G112) glasses and their crystalline phases has found that both P-free glass and its crystalline phase show greater elastic moduli than their corresponding P-bearing samples. The cause for this phenomenon in glasses is related to the amorphous phase separation due to the addition of phosphorus, the formation of weaker P-O-Si linkage, and a decrease in cohesion due to part of Ca2+ ions being captured by phosphate structural units. For the crystalline phases, the weaker moduli for P-bearing sample have been correlated to the possible distortion in crystal structure caused by the substitution of P5+ for Si4+. Generally, all the glasses and their crystalline phases studied in this work have the Young’s moduli suitable for the application in implantation. This enables us to tailor a material with proper elastic properties and glass structure for a specified medical purpose by adjusting the CaO/P2O5 (for the Na2O-CaO-P2O5-SiO2 glasses) or CaO/Na2O (for the Na2O-CaO- SiO2 glasses) molar ratios of the sample, and the time for partial crystallization (for glass-ceramics ).