Dielectric Dispersions of Mixed Crystals Rb_1-x(NH₄)_xH₂PO₄and Rb_1-x(ND₄)_xD₂PO₄

Abstract

Dielectric dispersions in mixed crystals Rb 1- x (NH 4 ) x H 2 PO 4 (RADP, x =0.35) and Rb 1- x (ND 4 ) x D 2 PO 4 (D-RADP, x =0.35) were studied around their glass-freezing temperatures. The complex dielectric constants along the a - and c -axes have consistently been described by the Vogel-Fulcher law of the relaxation time τ=τ 0 exp { E /( T - T 0 )} with a Gaussian distribution of the energy parameter E around the mean value E 0 . The values of τ 0 , T 0 and E 0 of D-RADP are several times as large as those of RADP. No appreciable anisotropic character was found between the dispersions along the a - and c -axes in both RADP and D-RADP.