Effect of nanoconfinement on the kinetics of phase transitions in organic ferroelectric DIPAI

Linear and nonlinear dielectric properties of new organic ferroelectric diisopropylammonia iodide (DIPAI) introduced into porous aluminum oxide films have been studied in comparison with the properties of a bulk DIPAI. In DIPAI, in pores 300 and 60 nm in diameter, it has been found that the ferroelectric phase forms on heating and on cooling in the temperature range between two structural phase transitions above room temperature. No marked temperature hysteresis is observed for both the phase transitions. The boundaries of the intermediate polar phase in the nanostructured DIPAI is shown to shift to lower temperatures as the pore size decreases. For the bulk DIPAI, two structural transitions are observed on heating with the formation of an intermediate polar phase and only one transition below which the ferroelectricity forms is observed on cooling. This transition temperature is significantly lower than the corresponding temperature on heating. It is assumed that the observed differences of the phase transition in DIPAI in pores and in the bulk DIPAI are related to an acceleration of the kinetics of the phase transitions in the nanoconfinement conditions.