Rare‐Earth Aluminogermanate Glasses

The present study is a comparison of the properties of rare‐earth aluminogermanate and rare‐earth aluminosilicate glasses. Several properties have been measured, including density, transformation temperature, softening point, thermal expansion, Vickers hardness, magnetic susceptibility, Verdet constant, and IR transmission. The property data are discussed in relationship to the structure of these glasses and the field strength of the rare‐earth ions. The Vickers hardness numbers of the glasses are discussed using a unique theory of hardness which involves the relationship between hardness and atom/ion packing in material structures.