The intrinsic ⅛ lock-in improper ferroelectric phase in thiourea: dielectric susceptibility and hysteresis loop analysis

摘要: Abstract The complex dielectric constant of thiourea has been measured in the temperature range from 80 K to 300 with different measuring-field levels and frequencies, without d.c. biasing fields. interval between two peaks e*a(T) curve near 178 was found extrapolate 0.7 at zero measuring fields, which indicates that ⅛ ferroelectric lock-in phase is intrinsic a non-zero range. E-T diagram region explored by investigating effects D-E hysteresis loops were investigated vicinity frequencies 0.5 Hz 5 mHz. observed clearly demonstrate difference “field-induced” mechanisms. Landau free energy analyzed shown produce self-consistent explanations experimental results successive transitions.