Glass Formation

The ability to form a glass, i.e., the ability to form bonds which lead to a vitreous network, appears periodically in the classification chart of the elements. Thus simple glasses containing only one kind of atom are formed by the elements of Group VI of the periodic table (O, S, Se, and Te). Only these elements are known to form monatomic (primary) glasses and they retain the ability to form a vitreous network when mixed or chemically bound to each other. The elements of Group VI also form binary glasses, i.e., glasses containing two kinds of atoms, with the elements of Groups III, IV, and V. Experimental evidence of the glassforming capacities of these elements and compounds is given; about twenty new glasses suggested by the foregoing were prepared in the author's laboratory. Binary glasses are also known to exist composed of an element of Group VII (F, Cl, I, or Br) and an element of one of Groups II, III, and IV or a transition element. Experimental evidence for these glasses is presented.