Studies on Jahn-Teller deformed structures of A2sup(I)PbCu(NO2)6 with a = K, Rb, Cs

Morphological studies including the polarizing miscroscope, neutron diffraction and infrared spectroscopy studies, in the latter case in dependence of temperature, gave some additional information about the Hahn-Teller deformation of the octahedron of the Cu11 ion during the phase transitions from a dynamic cubic structure (Tsub(h)-m3) to a two-dimensional dynamic structure with pseudotetragonal compressed octahedra (Dsub(2h)-mmm) and finally to a complete static case (lower than Dsub(2h)-mmm). Under the influence of pressure (up to 35 kbar), the two-dimensional dynamical case (pseudo tetragonal) of the Cs compound changes continuously into a cubic one at room temperature. (orig.)