High-pressure nano-seismology: Use of micro-ring resonators for characterizing acoustic emissions

Abstract

Microring resonator (MRR) ultrasound detectors provide orders of magnitude greater sensitivity and frequency range (to < 10 Pa, from DC to 100 s of MHz) than previously achieved in recording acoustic emissions from materials at high pressures. We characterize acoustic emissions from crystal-structural phase transitions in Si to pressures of 50 GPa, well beyond the brittle-ductile transition at room temperature, and find that the number of events increases nearly tenfold for each decade reduction in the duration of recorded events. The shortestduration events arrive in clusters, suggestive of a self-propagating, transformation-catalyzed process.

Resolving puzzles of the phase-transformation-based mechanism of the strong deep-focus earthquake

“…The modern acoustic emission approach combined with microstructural analyses is presented in refs. 10 , 14 , 15 . However, we will show that these semi-qualitative approaches cannot resolve the existing puzzles.…”