Novel Ferroic Materials with Functionally active Domain Walls

一些功能材料，如铁电体，包含称为“畴壁”的膜或片结构。几十年来，畴壁被认为是意义不大的微观结构成分而被忽视。现在很清楚，没有什么比这更远离真相了。事实上，畴壁通常具有独特的功能特性，与它们周围的畴完全不同：当材料的其余部分是绝缘的时，它们可以是导体或超导体;它们可以在非磁性晶体中显示磁序，并且当它们周围的基质是非极性时，它们可以拥有对齐的电偶极子。实际上，畴壁代表了一类新的片状纳米级功能材料，其目标是：1）合成和制备具有潜在激发畴结构的新型铁电材料; 2）通过适当的化学修饰（掺杂）来调节新材料和现有材料中的畴壁性质。该项目将涉及：（固态）合成工作，包括陶瓷加工;使用X射线和中子衍射确定晶体结构;以及使用一系列技术，如介电和阻抗谱、极化场和热刺激去极化电流测量，确定电气特性。

Some functional materials, such as ferroelectrics, contain membrane or sheet structures called "domain walls". For decades, domain walls were dismissed as being minor microstructural components of little significance. It is now clear that nothing could be further from the truth. Domain walls often, in fact, have unique functional properties that are completely different from the domains that they surround: they can be conductors or superconductors when the rest of the material is insulating; they can display magnetic order in non-magnetic crystals and they can possess aligned electrical dipoles when the matrix surrounding them is non-polar. In effect, domain walls represent a new class of sheet-like nanoscale functional material.The aim is to 1) synthesis and characterise novel ferroic materials with potentially exciting domain structures; and 2) to tune domain wall properties in new and existing materials be appropriate chemical modification (doping). The project will involve: (solid state) synthetic work, including ceramic processing; crystallographic structure determination using both x-ray and neutron diffraction; and electrical characterization using a range of techniques such as dielectric and impedance spectroscopy, polarization-field and thermally stimulated depolarization current measurements.