X-ray and neutron diffraction studies on the ferroelastic phase of Rb2Hg(CN)4

Abstract

Abstract The ferroelastic low temperature phase of Rb2Hg(CN)4 is trigonal, R[unk] c , with a 1 = 907.6(2), a 3 = 4605.0(2)pm, Z = 12. The structure was solved by Patterson and Fourier methods on the basis of X-ray and neutron diffraction data (906 and 665 independent reflections, resp.) The least-squares refinement yielded Rw -values of 0.046 and 0.048, resp. The structure deviates only slightly from that of the cubic high temperature spinel phase. The Hg(CN)4 tetrahedra exhibit an alternating twist around the trigonal axis of about 10.6°. Both rubidium positions are nearly octahedrally surrounded by CN groups. The ferroelastic behaviour is connected with a high librational mobility of the Hg(CN)4 tetrahedra.