摘要
The mixed modifier effect (MME) in the lithium-calcium borosilicate glasses, which have a composition of 0.4[(1−x)Li 2 O–xCaO]–0.6[(1−y)B 2 O 3 –ySiO 2 ] with x in the range of 0~1 and y in the range of 0.33~0.83, is investigated. The MME manifests itself as a positive deviation from linearity in the activation energy of electrical conductivity (Ea σ ) and as a negative deviation from linearity in the fraction of four-coordinated boron (N 4 ), glass transition temperature (T g ), dilatometric softening temperature (T d ), Vickers microhardness (H v ), dielectric constant (ε), and dielectric loss (tanδ). Moreover, the deviation, which exhibits a maximum at [CaO]/([CaO]+[Li 2 O])=0.5, is enhanced with increasing [SiO 2 ]/[B 2 O 3 ] ratio in the glass network. The observed MME in T g , T d , and H v are attributed to the bond weakening in the network; however, the MME in ε, tanδ, and Ea σ are caused by the obstruction of modifier transport in the glass network.