Conductivity of Ammonium Halides NH_4CI and NH_4F at Pressures up to 50 GPa

摘要

The resistivity of ammonium chloride (NH_4C1) and fluoride (NH_4F) are investigated at pressures from 20 to 50 GPa in the temperature range of 285 to 400 K. At temperatures between 340 and 380K a pressure induced transition into metallike state is found for ammonium chloride. The characteristic temperature and pressure of the transition is shown to depend on the duration of pressure treatment. At high pressures, the transition is metastable disappearing when pressure is applied during sufficiently long time. One more transition from low-resistance to high-resistance state was found at pressures about 27 GPa for NH_4C1 and 42 GPa for NH_4F, respectively.