摘要
应用放射性同位素法,研究了xLi_2O·(31.8-x)Na_2O·5.8Al_2O_3·62.4SiO_2(mol%)系玻璃中的Na^+自扩散温度范围为250～450℃。从实测数据,用数值法与图解法求得Na^+的自扩散系数D_(Na)~*。根据玻璃的组成和扩散温度,D_(Na)~*值变化于8.8×10^(-8)～1.1×10^(-11)cm^2s^(-1)。随着玻璃中Na_2O含量的减少,D_(Na)~*逐渐降低,显示明显的双碱效应。由不同碱离子的Dietzel场强之差,讨论了这种双碱效应。D_(Na)~*随温度指数上升,符合Arrhenius方程。据此方程,应用最小二乘法,获得扩散活化能E和指数前项D_o,E值约为79～91kJ/mol。
The Na^+ self diffusion in x Li_2O·(31.8-x) Na_2O·5.8 Al_2O_3· SiO_2 glasses (mol%) was studied at 250～450℃ by the radioactive isotope method. The Na^+ self diffusion coefficient D_(Na)~*, was numerically and graphically evaluated from the measured diffusion profile. D_(Na)~* varies between 8.8×10^(-8)～1.1×10^(-11)cm^2s^(-1), depending on the glass composition and the diffusion temperature. With increasing Na_2O-content in the glass, D_(Na)~* increases gradually, showing a pronouced mixed alkali effect, which was discussed on the basis of the difference between Dietzel's field strengths of the different alkali ions. D_(Na)~*, increases exponentially with the temperature and obeys Arrhenius equation. According to this equation the activation energy E and the preexponential term D_0 were evaluated by using the least square method. The value of E is about 79～91 kJ/mol.
关键词
玻璃
钠离子
自扩散
LI2O
NA2O
sodium ion
self diffusion
activation energy
glass
concentration dependence
mixed alkali effect: radioactive isotope method
