Correlation between thermal expansion coefficient and interionic interaction parameter in ZnO–Bi₂O₃–B₂O₃ glasses

Abstract

The volume thermal expansion coefficients (β) in 50–300°C of xZnO–yBi₂O₃–zB₂O₃ glasses (x = 10–65, y = 10–50, z = 25–60 mol %) were measured and the refractive index-based interionic interaction parameters A(n_o) were estimated from oxide ion electronic polarizabilities to acquire deeper insight into the relationship between the electronic polarizability and chemical bonding state of oxide glasses. The glasses have relatively large values of β = 210–289 × 10⁻⁷ K⁻¹, and the substitution of ZnO for B₂O₃ and the increase in Bi₂O₃ content result in an increase in β. The values of A(n_o) decrease with the substitution of ZnO for B₂O₃ and the substitution of Bi₂O₃ for ZnO. An almost linear correlation was observed between β and A(n_o), i.e., the volume thermal expansion coefficient decreases with increases in the interionic interaction parameter. A good correlation was also observed between A(n_o) and the refractive index-based optical basicity Λ(n_o). The interionic interaction parameter is helpful for understanding the chemical bonding state of oxide glasses.