Dynamic Nonlinear Response of Diglycine Nitrate Crystals in the Vicinity of Phase Transition Point

Nonlinear dielectric response of diglycine nitrate (DGN) crystal was investigated via measurements of linear, nonlinear dielectric susceptibilities and ferroelectric hysteresis loops. The behaviour of the third order susceptibility agrees with predictions of the thermodynamic theory of the continuous ferroelectric phase transitions. The second order susceptibility and hysteresis loops points at presence of the internal electric bias field. DGN has appeared to be electrically very “soft” within the ferroelectric phase, but it hardens at the phase transition point and remains hard above it.