Nuclear Forward Scattering of 121Sb as a local probe of ferroelectricity and phase transitions in SbSI

In this experiment, we aim to investigate the local environment of 121Sb in the multifunctional compound SbSI with Nuclear forward scattering (NFS), clarifying the nature of its phase transition(s) from 280 K up to 430 K. At room temperature, this system displays a ferroelectric (FE) state which originates from a polarization of Sb3+ bonds along the c polar axis of the structure. Above 298 K, however, it remains unclear whether the system undergoes a direct FE to paraelectric (PE) transition or passes through an intermediate antiferroelectric (AFE) phase before reaching the PE state above 410 K. Considering our preliminary electric field gradients (EFG) calculations for Sb atom in SbSI in its three different configurations, we propose temperature-dependent NFS experiments at ID14, exploiting the high brilliance of the ESRF synchrotron, to resolve unambiguously the phase sequence and transition temperatures.