RELATIONS BETWEEN MELTING-POINT, GLASS-TRANSITION TEMPERATURE, AND THERMAL-EXPANSION FOR INORGANIC CRYSTALS AND GLASSES

Thermal expansion coefficients correlate with a number of physical properties of crystals. Cubic ionic insulators that have two completely filled sets of lattice sites have a maximum value for the product of the coefficient and melting point. Expansion is diminished by the presence of various internal degrees of freedom, singly or in combination. These factors depend upon the array, band gap, bond length, and character and coupling between orbital sets. For screwlike chain structures and glasses αT 2m is a constant.