Studies on the role R2On (R = Ga and Cr, n = 3; R = Nb and Ta, n = 5) in 0.5Li2O·0.5{xR2On·(1 - X)B2O3} glass system

Abstract

The influence of the addition of R2On (R = Ga and Cr, n = 3; R = Nb and Ta, n = 5) on the thermal, electrical and structural properties of 0.5Li2O·0.5{xR2On·(1 - x)B2O3} glassy systems has been investigated. Results of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) have shown that Ga2O3 is in 4-coordination, Nb2O5, Ta2O5 and Cr2O3 are in 6-coordination in the above ternary glasses. Ga2O3, Nb2O5 and Ta2O5 act as both a network former and modifier at different ranges of composition . With the incorporation of Ga2O3, Nb2O5 and Ta2O5 into lithium borate binary glasses, the dc conductivity of the ternary systems shows two maxima which are due to the increase in the radius of the network doorway and the network modification effect, respectively. For 0.5Li2O·0.5{xGa2O3·(1 - x)B2O3} system, the glass transition temperature (Tg) decreases with the increase in Ga2O3 content. For 0.5Li2O·0.5{xNb2O5·(1 - x)B2O3} system, Tg reaches a minimum at the composition corresponding to Z = Nb2O5 content = 0.5 × 100 mol% = 0.2 mol%. When Z > 0.4 mol%, Tg increases with the increase in Nb2O5 content. Furthermore, the addition of Cr2O3 and Ta2O5 into lithium borate glass causes an increase in Tg. © 1998 Elsevier Science S.A. All rights reserved.