Ferroelectricity and phase transitions in tris (dimethylammonium) nonabromodiantimonate (III)

The crystals of tris (dimethylammonium) nonabromodiantimonate (III) (DMABA) were grown which show two phase transitions at 164 and 228 K. Below 164 K the crystal possesses the ferroelectric properties. At room temperature the crystal is isomorphous with the chlorine derivative: the space group P21/a, a = 14.612(8), b = 9.228(4), c = 10.005(8) Å, β = 94.91(6)°, Z = 2. The substantial differences between bromine and chlorine compounds result, most probably, from the fact that NH2 … Br hydrogen bonds are slightly weaker than NH2 … Cl bridges.