In situ investigation of structural change upon subjecting ferroelectric thin films to an electrical fields.

Strain in ferroelectric thin films has a pronounced effect on the functional properties of materials. The lead-free ferroelectric SrxBa1-xNb2O6 (SBN) has a flexible tetragonal tungsten bronze crystal structure which offers the tuning of its functional properties. From earlier beam times a fundamental understanding of the nucleation and growth of SBN thin films prepared by CSD has been reached. We will now conduct in situ X-ray diffraction studies on pre-made films, with different orientations and inherent strain, to identify and quantify the structural changes when exposed to an electrical field and possibly also coupled with heating above the Curie temperature. For these studies, films with both in-plane and out-of-plane polarization, and different induced strains from the substrate will be used. The data will be coupled with ex situ ferroelectric measurements of the thin films to correlate the strain, structural changes, and ferroelectric properties.

铁电薄膜中的应变对材料的功能特性具有显著影响。无铅铁电材料SrxBa1-xNb2O6（SBN）具有柔性四方钨青铜晶体结构，可对其功能特性进行调控。此前基于同步辐射束流实验，学界已对化学溶液沉积（Chemical Solution Deposition, CSD）制备的SBN薄膜的形核与生长机理形成了基础认知。本研究将对具有不同取向与本征应变的预制薄膜开展原位X射线衍射（X-ray diffraction, XRD）测试，以识别并量化薄膜在电场作用下的结构变化，若条件允许还将结合高于居里温度的加热处理开展协同实验。本次研究将采用同时具备面内与面外极化、且衬底引入不同诱导应变的薄膜样品。后续将结合本次实验获取的测试数据与薄膜的非原位铁电性能测试结果，建立应变、结构变化与铁电性能三者之间的关联机制。