Low-Temperature Phase in Superionic Conductor Ag3SBrxI1-x

The γ–β phase transition and crystal structure of the superionic conductor Ag 3 SBr x I 1- x are investigated by the X-ray diffraction and thermal analysis methods. The room temperature β-phase of Ag 3 SBr x I 1- x (0≤ x ≤1) belongs to the cubic system with the space group P m 3 m . In the range 0≤ x <0.29, the low-temperature γ-phase of Ag 3 SBr x I 1- x shows an ordered arrangement of Ag atoms, which are located at one of the four positions obeying the symmetry of the rhombohedral space group R 3. A new low-temperature γ-phase of Ag 3 SBr x I 1- x is found in the range 0.29≤ x ≤0.83. This phase belongs to the orthorhombic system, and the space group is P n m 2 1 or P n m m . Another new low-temperature γ-phase of Ag 3 SBr x I 1- x , which belongs to the monoclinic or triclinic system, is also found in the range 0.83< x <1.