Glass behaviour in the solid solution of deuterated betaine phosphate0.15 betaine phosphite0.85

Abstract

For a deuterated solid solution of 15% antiferroelectric betaine phosphate (BP) and 85% ferroelectric betaine phosphite (BPI), measurements of the dielectric permittivity at frequencies 20 Hz<<1 MHz are reported. The freezing phenomena in DBP0.15DBPI0.85 reveal the characteristics of a transition into a dipolar glass state with peculiarities due to the quasi-one-dimensional structure. Using the Kutnjak model a glass temperature of 25 K is estimated for deuterated DBP0.15DBPI0.85 and one of 10 K for protonated BP0.15DBPI0.85. The relaxation time distribution extracted from the experimental data by means of Tikhonov regularization and calculated in the region of the dielectric dispersion shows an asymmetric behaviour especially at lower temperatures, which is interpreted as being caused by a Gaussian distribution of activation energy and double-well potential asymmetry as well.