Novel broken symmetry phase from N2O at high pressures and high temperatures -: art. no. 135504

Simple molecular solids become unstable at high pressures, typically transforming to dense framework and/or metallic structures. We report formation of an unusual ionic solid NO+ NO3- (nitrosonium nitrate) from N2O at pressures above 20 GPa and temperatures above 1000 K. Synchrotron x-ray diffraction indicates that the compound crystallizes with a structure related to the aragonite form of CaCO3 and NaNO3. Raman and infrared spectroscopic data indicate that the structure is noncentrosymmetric and exhibits a strong pressure dependent charge transfer and orientational order.