Phases in antiferroelectric-side Rb1-x(Nd4)xD2AsO4 mixed crystals

Dielectric measurements in the mixed ferroelectric (FE)-antiferroelectric (AFE) system Rb1-x(ND4)(x)D2AsO4 (DRADA-x) (for ammonium concentrations x=0.39, 0.55, and 0.69) are reported, The phase coexistence of paraelectric (PE) and antiferroelectric (AFE) phases is confirmed in both x=0.55 and 0.69 crystals. A phase coexistence of deuteron-glass (DG) and antiferroelectric orderings is evidenced by the weak frequency dispersions (which occur below similar to 100 K) in both dielectric permittivities (epsilon'(a) and epsilon"(a)) for x=0.39 crystal. The temperature-dependent data epsilon"(a)(f,T) proves the existence of an electric dipolar relaxation process forming among the antiferroelectric domains below similar to 100 K.