Structural property of CsCl-type sodium chloride under pressure

The structure and equation of state of CsCl-type sodium chloride have been determined using high-pressure powder X-ray diffraction from 32 to 134 GPa. The CsCl-type phase remains stable over this entire pressure range. Pressure–volume data can be fitted with a Vinet equation of state with K30 GPa=135.1 GPa, K′30 GPa=3.9, and V30 GPa=27.70 Å3. The nearest-neighbour distance between sodium and chlorine atoms decreased as pressure increased. Significant discrepancies of nearest-neighbour distance between previous theoretical predictions and this study were observed at pressures higher than 70 GPa.