Scaling dielectric data on ${\mathrm{Rb}}_{1\mathrm{-}\mathit{x}}$(${\mathrm{NH}}_4$${)}_{\mathit{x}}$${\mathrm{H}}_2$${\mathrm{PO}}_4$ structural glasses and their deuterated isomorphs

Temperature- (T) and frequency- (ν) dependent dielectric losses on ${\mathrm{Rb}}_{1\mathrm{-}\mathrm{x}}$(${\mathrm{NH}}_4$ ${)}_{\mathrm{x}}$ ${\mathrm{H}}_2$PO ${}_4{}^{}{}_{}{}^{}$ single crystals (RADP), and their deuterated isomorphs (D-RADP), can be collapsed to single curves with a scaling variable E(T,ν). This applies for T sufficiently high that equilibrium is established within the sample-thermalization time. If E(T,ν) follows the Vogel-Fulcher law, the scaling will depend only on the freezing temperature $T_0$ and on the attempt frequency ${\nu }_0$. For RADP, values in excellent agreement with a study covering a very broad frequency range are thus obtained, while significantly different values apply to D-RADP.