Effect of halide ions on Li+ ionic conductivity in oxyhalo-borate glasses

Abstract

The electrical conductivity has been measured for the glasses in the system B2O3–Li2O–Li2X2(X = F, Cl, Br), where Li2O is replaced by Li2X2 with Li content kept constant. The conductivity decreases for F glasses and increases for Cl and Br glasses with increasing halide ion content, which is caused by the increase in the activation energy for F glasses and the decrease for Cl and Br glasses. The analysis of the activation energy in terms of the Anderson-Stuart model indicates that, with the increase in LiX, Δ Eb, (the electrostatic energy) increases for F glass, whereas ΔEs (the strain energy) and ΔEb decrease for Cl or Br glasses. The effects of F− and other halide ions are attributed to a stronger interaction between Li and F, and to expanded and weakened glass network due to accommodation of Br− and Cl− ions.