Study of the structural properties and phase transitions of LiCs1−x(NH4)xSO4 (x = 0.1 and 0.4) mixed crystals by 1H, 7Li, and 133Cs nuclear magnetic resonance

► The structural properties and phase transitions of the LiCs1−x(NH4)xSO4 mixed crystals. ► The effects of partially replacing cesium ions with ammonium ions. ► The disappear of the ferroelastic properties.