Dielectric critical slowing down in pentakis(imidazolium) undecabromodibismuthate(III): (C(3)N(2)H(5))(5)Bi(2)Br(11)

Abstract

Low frequency dielectric dispersion studies have been carried out for the ferroelectric pentakis(imidazolium) undecabromodibismuthate(III)- (C(3)N(2)H(5))(5)Bi(2)Br(11)-single crystal in the paraelectric phase in the radio-frequency region (100 Hz-1 MHz). The dielectric dispersion, observed for an electric field along the a-axis (P 2(1)/n space group), is characterized by a polydispersive nature close to the Curie temperature (T(c) = 155 K). The dielectric dispersion findings were analyzed accurately with the Cole-Cole formula. In the vicinity of the Curie temperature the process of the dielectric critical slowing down is clearly observed. Such a dynamic dielectric response is characteristic of ferroelectric crystals classified as 'order-disorder' type.