Reformulating Table Salt Under Pressure

摘要

Sodium chloride (NaCl), the main component of table salt, is the archetypical ionic compound of chemistry textbooks. The large electronega-tivity difference between the participating elements drives salt formation. Metallic sodium transfers electrons to chlorine, and the resulting positively and negatively charged ions are held together by electrostatic attraction-ionic bonds. At ambient conditions, NaCl crystallizes in the so-called rocksalt structure, a cubic array of Na and Cl atoms in equal proportions (1:1 stoichiometry) and with six-fold coordination. With increasing pressure, a structural phase transition to the cubic, eight-fold coordinated NaCl-B2 phase is observed at -30 GPa [(1) and references therein].