Evolution of the structure of Rb2ZnCl4 over the temperature range 4.2-310 K

X-ray diffraction is used to study the temperature dependence of the lattic e parameters and the sequence of structural realignments in crystalline Rb2 ZnCl4 over temperatures of 4.2-310 K. The appearance of and changes in the system of satellite reflexes indicative of structural ordering are studied. Below 74 K, on going into the monoclinic phase (space group A11a), anomali es are observed in the behavior of the lattice parameters, and superstructu ral reflexes develop with wave vectors q = a*/3 + b*/2 + c*/2 corresponding to an increase by a large factor in initial parameters a, b, and c of the Pnma-phase. (C) 1999 American Institute of Physics. [S1063-7834(99)03406-1] .