Study on the structural properties and relaxation mechanisms in LiRb1−x(NH4)xSO4 (x=0, 0.5, and 1) mixed crystals by 1H, 7Li, and 87Rb nuclear magnetic resonance

► The effects of replacing ammonium ions with rubidium on LiRb1−x(NH4)xSO4 ► The structural properties and phase transition temperatures of the LiRb1−x(NH4)xSO4. ► The orientation of the sulfate tetrahedral groups.