Properties of porous glasses with embedded ferroelectric materials

Abstract

Methods of introducing two ferroelectric materials, viz. NaNO2 and (CH3NH3)5Bi2Cl11 (PMACB), into porous glass matrices and the results of dielectric, pyroelectric, thermal expansion and SEM investigations are presented. The best filling degree was achieved for NaNO2 introduced from the melt, whereas a significantly worse filling effect was achieved for a water solution as the introducing agent. A splitting was observed in the temperature dependence of dielectric permittivity related to the incommensurate phase of NaNO2 embedded in porous glass from a water solution, whereas no incommensurate phase was observed in the case of glass filled with NaNO2 from the melt. The confined materials turned out to possess ferroelectric properties and exhibited phase transitions. The negative size effect was observed for porous glasses filled with NaNO2 and PMACB. The above conclusions are based on the anomaly of dielectric, pyroelectric and dilatometric properties observed in the phase transition regions.