Positive Temperature Coefficient of the Elastic Modulus of Glasses.

The temperature coefficient of the elastic properties of glasses is of great importance for glass components used as transmitters in control circuits, for compensation of thermal expansion. Glasses can have many advantages over other materials such as the wide range of compositions, electrical and thermal insulation, transparency, lack of reflection, workability, resistance to temperature, homogeneity, reproducibility of mechanical, electrical and magnetic losses, chemical durability, impermeability to gases, ease of sealing, etc. A positive sign is not normally found for the temperature coefficient of the elastic moduli of glasses. It is shown that the anomaly is a consequence of the glass structure and depends on an entropy effect.