网络修饰体对铝硅酸盐系玻璃微观结构的影响:第一性原理分子动力学模拟

Effects on structure of aluminosilicate glass with type of network modifier cations:ab-initio molecular dynamic simulations

铝硅酸盐玻璃体系是玻璃工业中的重要体系,具有较好的化学稳定性、较高的机械强度和低膨胀系数。本文采用第一性原理分子动力学模拟研究了几种网络修饰体对铝硅酸盐系玻璃的微观结构的影响,研究发现当M/Al=1/2(M=Ca,Mg)或者R/Al=1(R=Na,K)时,铝全部转变为铝氧四面体,此时玻璃结构并不像传统理论认为的形成一个完整的三维网络,而是存在一定数量的非桥氧。通过对径向分布函数,键角分布、配位数、Qn等方面的分析,讨论了网络修饰体的性质对Si以及Al的局部环境的影响。研究表明网络修饰体的电场强度(z/r^2)是影响铝硅酸盐玻璃微观结构的主要因素。网络修饰体在提供游离氧使网络解聚的同时,还有积聚断键的作用,并且电场强度越大,积聚作用越强,网络的连贯性越好。

Aluminosilicate glass plays an important role in the glass industry,due to its good chemical stability,mechanical strength,and low coefficient of expansion. The microstructure of aluminosilicate glass with different network modifier cations were studied by ab-initio molecular dynamic simulations. It is found that when the modifier cations M/Al = 1/2 or R/Al = 1（ M = Ca～（2＋、Mg～（2＋）,R = K～＋、Na～＋）,aluminium atoms have almost transformed into [AlO4]tetrahedrons,but there is a certain number of nonbridging oxygens existed,which is not consistent with previous theory. Based on the analysis of the radial distribution function,the bond angle distribution,coordination number and Qnetc.,the effects of local environmental properties of Si/Al from network modifier are discussed. The results show that the electric field strength（ z/r^2） of the network modifier is the main factor influencing the microstructure of aluminosilicate glass. When the network modifier provides free oxygen to break up the network,it also has the effect of attracting broken bonds,and the stronger the electric field is,the stronger the accumulation is,and the better the coherence of the network.