Dielectric response of potassium nitrate in a restricted geometry

The dielectric properties of nanocomposite materials (NCM) on basis of porous glasses with KNO3 embedded into the pores have been studied in the temperature interval 293 K-570 K and in the frequency diapason 0.1-107 Hz. The three types of porous glasses with average pore diameter 320 (PG320), 46 (PG46) and 7 (PG7) nm have been used for production NCM from melted KNO3. It is shown that dielectric permittivity demonstrates the essential growth in the high-temperature phase for all types of NCM. The temperature of the ferroelectric phase transition decreases at a reduction of average pore diameters and the temperature interval of stability of ferroelectric phase essentially enlarges. In case of NCM on basis of PG7 there is no any anomalies corresponding to the phase transition in this NCM and on cooling up to room temperature ferroelectric phase remains stable. From analysis of dielectric response, the relaxation process responsible for the ferroelectric phase transition has been detected and the temperature dependencies of process parameters have been determined.