Microwave dielectric dispersion in RbD2PO4crystals

Abstract
The paper presents the results of the investigation of the dielectric dispersion in RbD2PO4 in the vicinity of the low-temperature ferroelectric phase transition. It is shown that the dielectric dispersion of Debye type along the b-axis in frequency range 50 MHz to 50 GHz is caused by the single relaxational soft mode which at Tc2=324 K softens to 0.4 GHz. The results confirm the quasi-one-dimensional nature and the order-disorder type of the ferroelectric phase transition.