Spectroscopy at very high pressures. Part 8.—An infrared study of shear-stress-induced transitions in ammonium and sodium nitrates

Abstract

Bridgman showed that some second-order phase transitions which do not occur under conditions of hydrostatic compression can take place when, in addition, a shear stress is applied. In this paper we show that a diamond anvil cell used without a gasket around the sample is an excellent device for studying shear-stress-induced transitions. This is illustrated by i.r. spectra of NH₄NO₃ and NaNO₃, for each of which a new phase was detected.