ESTIMATION OF THERMAL-EXPANSION COEFFICIENT OF SILICATE-GLASSES WITH COMPOSITIONAL PARAMETER

Thermal expansion parameter, alpha(p), which is based on the potential energy between cation-anion, has been proposed to estimate the therma l expansion coefficients of oxide glasses. alpha(pi) (i for the ith sp ecies) is defined as alpha<INF>pi</INF> = n<INF>i</INF>/n<INF>i</INF> - 1 INF>+i</INF>Z<INF>-i</INF>/r<INF>eqi</INF>)<SUP>-1 </SUP>by charge Z, Born exponent n and the equilibrium interatomic distance r(eq) cal culated from the ionic radius. Ln this study, or, of multicomponent ox ide glasses were calculated on the assumption that the additivity of a lpha(p) was hold for the glasses, and the applicability of alpha(p) fo r the glasses was investigated. As a result, it mas revealed that many silicate glasses, including borosilicate and aluminosilicate glasses, could be divided by cation valence of network modifier oxide and an a pproximately linear relationship existed between the thermal expansion coefficient and cr,in each division. It became possible to estimate t he thermal expansion coefficient of silicate glasses accurately using the relations obtained in this study.