Broadband dielectric spectroscopy of betaine phosphate(0.03) betaine phosphite(0.97) crystals in the vicinity of the ferroelectric phase transitions

摘要

The dielectric properties of ferroelectric hydrogen bonded betaine phosphate(0.03) betaine phosphite(0.97) (BP0.03BPI0.97) have been investigated in the region of the ferroelectric phase transition. Dielectric dispersion was investigated in the frequency range up to 53 GHz. The distribution of relaxation times has been calculated directly from the dielectric spectra. The parameters of the double-well potentials of the hydrogen bonds, the local polarization distribution function and the average (macroscopic) polarization have been extracted from the dielectric measurements data. At low temperatures the freezing phenomena in BP0.03BPI0.97 revealed the complex dielectric permittivity behavior characteristic for transition into the dipolar glass state. The activation energy of this low temperature process was equal to E-b = 558 K (0.048 eV) and the freezing temperature was estimated on 30 K.