Size effects in KDP-porous glass ferroelectric nanocomposites

Abstract

An influence of the size effect on the phase transition temperature in potassium dihydrogen phosphate (KDP)-porous glass nanocomposites was studied in this work. Results of the dielectric measurements in a wide temperature range for KDP crystals embedded in porous glasses are presented. The phase transition temperature shift toward higher temperatures was observed for KDP embedded in porous glasses with the mean value of the pore size of 312 and 160 nm, whereas for smaller pore sizes (71 and 23 nm) the phase transition temperature decreased. The phase transition temperature dependence of the mean values of the pores dimensions of KDP-porous glass nanocomposites is the experimental evidence showing the non-monotonical character of the size effect on the phase transition temperature in ferroelectrics particles. It was found that the dielectric permittivity of KDP embedded into the porous glasses with the mean values of pore sizes of 160 nm and 312 nm practically did not depend on frequency, whereas for KDP embedded into the pores with dimensions of 71 nm and 23 nm a dispersion of the dielectric permittivity is observed in both para- and ferro-electric phases.