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[Ge.sub.x][As.sub.y][Se.sub.1-x-y] glasses are prepared with mean coordination (MCNs) and the elastic moduli of the glasses are estimated from the shear and compressional wave velocities. Two elastic transition thresholds are observed simultaneously and the elastic moduli of two groups of samples with the same MCN but different compositions have shown that the chemical compositions have an impact on the elastic properties.

We have prepared GexAsySe1-x-y glasses with mean coordination numbers (MCNs) from 2.2 to 2.86. Tg was found to generally increase with increasing MCN while the glass density showed a maximum at MCN≈2.45 and a minimum at MCN≈2.65. The elastic moduli of the glasses were estimated from the shear and compressional wave velocities measured by ultrasonic pulse interferometry. For the first time we simultaneously observed two elastic transition thresholds, the first at MCN≈2.45 and the second at MCN≈2.65, which appear closely correlated with changes in the glass microstructure. The elastic moduli of two groups of samples with the same MCN=2.4 and 2.64 but different compositions suggest that the chemical compositions also have an influence on the elastic properties. [ABSTRACT FROM AUTHOR]