Crystal structure of NiO under high pressure

Eto, Tetsujiro*; Endo, Shoichi*; Imai, Motoharu*; Katayama, Yoshinori; Kikegawa, Takumi*

The pressure effect on the lattice constant of NiO with the rhombohedral distorted B1 structure was studied up to 141 GPa by angle-dispersive x-ray diffraction using synchrotron radiation and an imaging plate, with reference to a recent theoretical calculation within the density-functional formalism with the local-spin density approcximation. The lattice constant and , expressed in the hexagonal lattice, decrease monotonously with increasing pressure. The axial rage decreases monotonously with increasing pressure, indicating the enhancement of the rhombohedral distortion. The signiifcant change of above 60 GPa suggested by the calculation was not observed.