Structural Behavior of Non-Oxide Perovskite Superconductor MgCNi${}_3$ at Pressures up to 32 GPa

Abstract

We report the pressure dependence of the structural parameters of the non-oxide perovskite superconductor MgCNi${}_3$ up to 32 GPa using a diamond anvil cell and synchrotron x-rays at room temperature. The structure of the compound remains in the Pm-3m cubic symmetry throughout the pressure range. The bulk modulus $B_0=156.9\pm 0.2$GPa with $B_0^{\prime }=9.8$obtained by fitting the pressure-volume data is in good agreement with theoretical calculations reported earlier. An anomalous shift of the (111) and (200) lines observed above 9 GPa indicates a possible local short range distortion that is consistent with earlier studies.

9 Pages, 3 Figures, 1 Table