Ultrahigh elasticity and anomalous softening of α-Ag2S under pressure

Inorganic semiconductors are often brittle at room temperature, but alpha-Ag2S was recently observed to own extraordinary metal-like ductility and reversible pressure-induced isosymmetric phase transitions. Here, we report findings from first-principles calculations that alpha-Ag2S exhibits ultrahigh elasticity and anomalous softening under pressure. Such unusual mechanical behaviors have their underlying origins. Subsequent experimental measurements confirm that alpha-Ag2S is very soft with a large elastic strain limit of similar to 1.7%. This study provides crucial insights into the understanding of high elasticity in semiconducting materials, which is beneficial for the design of semiconductors for flexible and stretchable electronic devices.