BaO对B_2O_3-La_2O_3-ZnO玻璃结构和析晶的影响

Influence of BaO on Structure and Crystallizaion in Glass B_2O_3-La_2O_3-ZnO

B_2O_3-La_2O_3-ZnO玻璃(简记BLZ玻璃)易分相失透。为了抑制这种由La^(3+)积聚引起的失透,常在BLZ玻璃中加人一些高价金属氧化物,如Nb_2O_5,Ta_2O_5等,但使玻璃着色,熔制更为困难。本实验发现,BaO能够抑制BLZ玻璃中La^(3+)的积聚,改善玻璃形成性能;同时,BaO可以降低玻璃熔制温度,不引起玻璃着色。本文利用NMR,DTA等测试方法,研究了BaO对玻璃网络结构和析晶行为的影响,探讨了BaO抑制La^(3+)积聚的原因。

Glass B_2O_3-La_2Q_3-ZnO (BLZ glass) has a strong tendency to devitrify from La^(3+) aggregation.To control glass crystallization, some metal oxides with high valence, such as Nb_2O_5 and Ta_2O_5, areusually added; however, those metal oxides would lead the glass to significant colouring and elee-vated melting temperature. In this ecsearch, the author applied BaO to control glass crystallization. By means of NMR,DTA and other measurements, the innuences of BaO on the network structure and crystalling behav-ior in BLZ glass are studied, and the mechanism of BaO to inhibit the La^(3+) aggregation is discussed.The results showed, BaO in small quantity could increase the amount of (BO_4) tetrahedra, enhancecrystalling temperature, and do not cause the volume expansion of oxygen structure. Through study,it is believed, BaO in small quantity could not only increase the amount of (BO_4) tetrabedra, but alsocause the formation of (ZnO_4) tetrahedra into network, decrease the content of 'non-bridging' oxy-gen, and reduce the spacing in glass network, thus strengthenning the bonding of network structureand controlling the glass crystallization. Besides, the author suggested that the main cause of BaO to inhibit the La^(3+) aggregation is the reduction of 'non-bridging' oxygen number surroundingLa^(3+) ions.