Reinvestigation of Low-Temperature Phase Transitions in Rb2ZnBr4

Abstract

Low-temperature phase transitions in Rb 2 ZnBr 4 single crystal were reinvestigated by means of neutron and X-ray diffractions. Below 116 K some superlattice reflections appeared at the same position (h/2, k/2, 0) as in other members of Rb 2 ZnCl 4 group crystals, where h and k denote the Miller indices in the normal phase (space group P m c n ). The temperature dependence of the integrated intensity of the superlattice reflection changed below 78 K. However, the anomaly around 50 K reported previously was not observed. Below 116 K an incommensurate phase as reported for K 2 ZnCl 4 was not detected. The space group of phase between 78 and 116 K was directly confirmed to be C 1 c 1 by the verification of extinction rules of X-ray diffraction.