Fabrication and physical properties of ferroelectrics confined in nanoporous materials

计划在纳米多孔基质（多孔玻璃、人造蛋白石、沸石、MCM-41、MCM-48和SBA-15型介孔材料）中制备和研究特征尺寸在0.7至100 nm范围内的铁电材料。将制备NaNO2， BaTiO3和KDP纳米结构。该项目的主要目标是利用核磁共振和声学方法研究尺寸对铁电纳米结构相变的影响（相变温度的变化、尺寸诱导的铁电相变抑制、相变涂抹）。这允许研究微观参数的变化（局部电场和磁场分布，化学键合）和在受限铁电体中有序参数的动力学。孔隙几何结构（多孔玻璃中的不规则三维孔隙网络，人工蛋白石、沸石和介孔材料（如MCM 41）中的规则孔隙晶格）的作用将被研究。实验结果将与基于小颗粒和薄膜中铁电相变的现象学处理的理论预测进行比较。

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.