High pressure X-ray diffraction study of potassium azide

Crystal structure and compressibility of potassium azide was investigated by in-situ synchrotron powder X-ray diffraction in a diamond anvil cell at room temperature up to 37.7 GPa. In the body-centered tetragonal (bct) phase, an anisotropic compressibility was observed with greater compressibility in the direction perpendicular to the plane containing 1 N-3(-) ions than directions within that plane. The bulk modulus of the bct phase was determined to be 18.6(7) GPa. A pressure-induced phase transition may occur at 15.5 GPa. (C) 2011 Elsevier Ltd. All rights reserved.