Acid-Base Estimation of Molten Glasses by Emf's of Concentration Cell

测定氧化物玻璃氧离子活度的方法很多，如气相溶解度的测定、过渡金属离子的光吸收测定、氧化还原平衡的测定、浊点延伸效应的测定和浓差电池电动势的测定。最后一种方法是研究熔融状态的最有用的方法。浓差电池的电动势，例如：PT：&lt；O_2&gt；|&lt；Na_2&gt；0.2&lt；B_2&gt；&lt；O_3&gt；(参考)||&lt；Na_2&gt；O-&lt；B_2&gt；&lt；O_3&gt；|&lt；O_2&gt；：PT由Nernst型方程给出。实验熔体的氧离子活度可由方程[&lt；O^(2-)&gt；]=exp(-2Fe/RT)计算。铂：&lt；O2&gt；|&lt；Na_2&gt；0.2&lt；B_2&gt；&lt；O_3&gt；||x&lt；R_2&gt；O-(1-x)&lt；B_2&gt；&lt；O_3&gt；|&lt；O_2&gt；|&lt；|x&lt；R_2&gt；O-(1-x)Si&lt；O_2&gt；|&lt；O_2&gt；|&lt；O_2&gt；：PT(其中R=Li，Na，K和Cs)是用双铂坩埚制成的电桥测量的，其中较小的一个有针孔。氧离子活度随碱金属氧化物含量的增加而增加，其顺序为&lt；Li^&gt；&lt；Na^&gt；&lt；&lt；K^&gt；&lt；&lt；Cs^&gt；然而，对于Li-和Na-硼酸盐体系，在x=0.2附近有一个明显的极小值，这表明即使在熔体中也存在硼反常。X&lt；Na_2&gt；O(1-x)&lt；B_2&gt；&lt；O_3&gt；熔体(x=0.1-0.4)中的&lt；Ni^(2)&gt；Ni^0&gt；和&lt；Sb^(5)&gt；随着氧化钠含量的增加，O_3&gt；呈负增长。溶剂化能计算表明，随着熔体碱度的增加，这些离子与氧离子的反应活性变大。

There have been many attempts to determine the oxygen ion activity of oxide glass, such as measurement of gaseous solubility, optical absorption of transition metal ions, determination of oxidation-reduction equilibrium, measurement of nephelauxetic effect and emf measurement of concentration cell. The last one is the most useful method for the molten state. The emf of a concentration cell, for example, Pt: <O_2> | <Na_2> 0.2 <B_2> <O_3> (reference)|| <Na_2> O- <B_2> <O_3> | <O_2> :Pt is given by the Nernst type equation. The oxygen ion activity of the test melt can be calculated from the equation, [ <O^(2-)> ]=exp(-2FE/RT). The emfs of Pt: <O_2> | <Na_2> 0.2 <B_2> <O_3> ||x <R_2> O-(1-x) <B_2> <O_3> | <O_2> :Pt and Pt: <O_2> | <Na_2> 0.2Si <O_2> ||x <R_2> O-(1-x)Si <O_2> | <O_2> :Pt (where R=Li,Na,K and Cs) were measured by using the electrolytic bridge made of double platinum crucibles in which the smaller one has a pinhole. The oxygen ion activity increases with increasing alkali oxide content as well as with the order of <Li^+> < <Na^+> < <K^+> < <Cs^+> . However, for Li- and Na- borate systems there is the respective clear-cut minimum around x=0.2, which suggests the existence of the boron anomaly even in the melt. The standard reduction potentials of <Ni^(2+)> / <Ni^0> and <Sb^(5+)> / <Sb^(3+)> in x <Na_2> O.(1-x) <B_2> <O_3> melt (x=0.1-0.4) referred to the platinum oxygen electrode in <Na_2> 0.2 <B_2> <O_3> increased negatively with increasing sodium oxide content. The solvation energy calculation showed that the reactivity between these ions and oxygen ions became larger with increasing basicity of the melt.