Rigidity Percolation in the Germanium-Arsenic-Selenium Alloy System

We have measured the elastic constants of two series of glasses in the Ge-As-Se system. Each series consisted of samples whose compositions were chosen to produce an average atomic coordination ($〈r〉$) which ranged from 2 to nearly 3. Different local structures were produced by our making one series much higher in As content than the other. Despite this difference both series exhibited evidence of rigidity percolation near $〈r〉=2.4$.