New Insight into Phase Transitions of Porous Glass-Based Ferroelectric Nanocomposites

The results of XRD, FTIR and differential scanning calorimetry (DSC) studies of empty porous silica matrices filled with binary mixtures of K_1-xAg_xNO₃ (x = 0.05, 0.10) are reported in comparison with those obtained for bulk salts in the temperature range of structural phase transitions. Scanning electron microscopic data of the studied empty macroporous and microporous glasses confirmed differences in the pore morphology associated with the presence of silica gel. Accordingly, XRD and FTIR samples contain crystalline phase of KNO₃ and AgNO₃. The results of calorimetric investigation of porous glasses filled with binary mixtures of K_1-xAg_xNO₃ (x = 0.05, 0.10) are presented. The results show that in the K_1-xAg_xNO₃ nanocomposites, anomalies associated with phase transitions were detected. An influence of the mean value of pores sizes on the ferroelectric phase transition temperatures of K_1-xAg_xNO₃ nanocrystals embedded into the porous matrices was determined. The impact of pore space structure on the phase transitions of ferroics nanocomposites was discussed.