The nature of anharmonicity and phase transition in SbSBr crystal

Abstract

The ferroelectric crystal structure of SbSBr is composed of [Sb(S, Br)]_∞ chains parallel to the [001] axis. In paraelectric phase, the crystal structure is disordered. The theoretical investigation of dependence of potential energy V_P (z) of Sb atoms on amplitudes of B_1u vibration symmetry coordinates along c (z)-axis have showed that each atom is shifted from the xy mirror plane by up or down along [001]. The theoretical investigation of the average potential energy of all Sb atoms in unit cell revealed that in paraelectric phase in region of phase transition has double-well shape. This strong anharmonicity of is created by interaction between phonons.

Keywords:

• SbSBr crystals
• phase transition
• potential energy of atoms
• anharmonicity
• paraelectric phase