Fabrication and physical properties of ferroelectrics confined in nanoporous materials

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Fabrication and studies of ferroelectric materials within nanoporous matrices (porous glasses, artificial opals, zeolites, mesoporous materials of type MCM-41, MCM-48 and SBA-15) with characteristic sizes in the range of 0.7 to 100 nm are planned. NaNO2, BaTiO3, and KDP nanostructures will be prepared. The main goal of the project consists in studying size effects on phase transitions in ferroelectric nanostructures (shifts of the phase transition temperatures, sizeinduced suppression of ferroelectric phase transitions, smearing the phase transitions) using NMR and acoustic methods. This allows to investigate changes in the microscopic parameters (local electric and magnetic field distribution, chemical bonding) and in the kinetics of the order parameter in confined ferroelectrics. The role of pore geometry (irregular three-dimensional pore network in porous glasses, regular pore lattices in artificial opals, zeolites and mesoporous materials, like MCM 41, will be investigated. The experimental results will be compared with theoretical predictions on the basis of a phenomenological treatment of ferroelectric phase transitions in small particles and thin films.