Phase transitions of SС(NH$_{2}$)$_{2}$ ferroelectrics in Al$_{2}$O$_{3}$-based nanoporous matrices

Temperature dependences of the linear permittivity $\varepsilon'$ and the third harmonic amplitude $\gamma_{3\omega}$ of composites prepared by introducing ferroelectrics SС(NH$_{2}$)$_{2}$ into matrices of porous aluminum oxide Al$_{2}$O$_{3}$ with pore sizes 60 and 100 nm are determined. It is found that temperature $T_c$ of the ferroelectric phase transition and the temperature $T_i$ of the phase transition from incommensurable phase to the paraphrase increase significantly. The transition shifts increase as pore diameters decrease.