We study relaxation under pressure of a radiation-amorphized material. The volume of zircon, $\mathrm{Zr}\mathrm{Si}{\mathrm{O}}_4$, amorphized by natural radiation over geologic times, was measured under high pressure using the precise strain-gauge technique. The volume shows logarithmic relaxation as a function of time. We compare the measured relaxation with the logarithmic relaxation of other different systems, and discuss the commonality of behavior in these systems in terms of local relaxation events that relax stress on a microscopic scale. We propose that logarithmic relaxation arises as the result of the elastic feed-forward interaction mechanism between local relaxation events.

• Received 3 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.012103