Crystal structure and phase transitions of the ferroelectric antimony sulfoiodide SbSI. Part II. Crystal structure of SbSI in phases I, II and III

Crystal structure of antimony sulfoiodide SbSI has been determined in all three phases: ferroelectric, antiferroelectric and paraelectric. In the ferroelectric phase III crystals of SbSI are polar in the space group Pna2(1) in agreement with previous reports. Above the Curie point at 298 K SbSI in phase II becomes antiferroelectric in the space group P2(1)2(I)2(1) and alternating arrangement of polar double chains parallel to [001]. Only above the high temperature phase transition at 410 K, the crystals of SbSI become centrosymmetric in the space group Pnam.