CRYSTAL-STRUCTURE AND PHASE-TRANSITIONS OF THE FERROELECTRIC ANTIMONYSULFOIODIDE SBSI - PART II - CRYSTAL-STRUCTURE OF SBSI IN PHASE-I, PHASE-II AND PHASE-III

Crystal structure of antimony sulfoiodide SbSI has been determined in all three phases: ferroelectric, antiferroelectric and paraelectric. I n the ferroelectric phase III crystals of SbSI are polar in the space group Pna2(1) in agreement with previous reports. Above the Curie poin t at 298 K SbSI in phase II becomes antiferroelectric in the space gro up P2(1)2(I)2(1) and alternating arrangement of polar double chains pa rallel to [001]. Only above the high temperature phase transition at 4 10 K, the crystals of SbSI become centrosymmetric in the space group P nam.