非晶态离子导体Li2B2O4晶化前期的离子导电性

本文研究了非晶态离子导体Li₂B₂O₄的离子电导率与温度的关系,特别着重于晶化前期的离子迁移特性。当温度低于T_K(≈310℃)时,离子电导率遵从Arrhenius关系。当高于晶化温度(≈411℃)时,以晶态中的离子迁移为主。在T_kc时,电导率偏离热激活机制呈反常增高。我们把这一过程称为晶化前期过程。可以用自由体积模型进行描述。晶化前期又可分为两部分:当温度低于、T_p(≈380℃)时,由于自由体积的重新分布,导致了电导率的增高;当T>T_p时,出现了少量微晶,但晶化量小于5%,由于非晶母体与微晶之间的界面效应使得离子导电性显著增强。可以通过室温淬火,把晶化前期非晶态的状态保持到室温,从而有可能制备出离子电导率高于纯非晶态的材料。 关键词：

IONIC CONDUCTION DURING PRE-CRYSTALLIZATION PROCESS IN AMORPHOUS IONIC CONDUCTOR Li2B2O4

The temperature dependence of ionic conductivity, especially the ion transport property during pre-crystallization process in amorphous ionic conductor Li₂B₂O₄ has been studied. When the temperature is lower than T_k(≈310℃), the ionic conduction obeys Arrhenius relation. Above the crystallization temperature T_c(≈411℃), the ion transport behaviour is dominated by the process in crystalline state. In the range T_kc, the ionic conductivity deviates from thermal excitation mechanism and is enhanced anomalously. This process is now called pre-crystallization process. It is found that the free volume model could be used to describe the ion transport properties. In pre-crystallization process there are two distinguishable steps. Below T_p(≈380℃) the ionic conductivity increase is due to the redistribution of free volume. While above T_p considerable enhancement of the ionic conductivity is caused by the in-terfacial effect between the crystallites and amorphous matrix because small amount of crystallites (less than 5%) were emerged. The pre-crystallization status of the amorphous could be remained at ambient condition by quenching the specimen to room temperature. Therefore it is possible to prepare material with higher ionic conductivity than that of pure amorphous.