Understanding magnetocaloric and electrocaloric effects using epitaxial films

使用外延膜了解磁热和电热效应

• 批准号: 226811039
• 负责人: Privatdozent Dr. Sebastian Fähler
• 金额: --
• 依托单位: Institut für Ionenstrahlphysik und Materialforschung
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/226811039?language=en
• 关键词: Understanding; magnetocaloric; electrocaloric; effects; using

There is a need for more energy-efficient refrigeration to reduce the environmental impact of todays lifestyle. Solid state refrigeration based on diffusionless transformation is a promising solution. Within our joint project we focus on materials exhibiting electrocaloric or magnetocaloric effects, i.e. where the application of an electric or magnetic field leads to a temperature change. In shape of thin films such materials might be used for on-chip ferroic cooling in microelectronics or micromechanical devices. The main goal of our experimental project is to understand ferroic cooling and in particular hysteresis losses on a microstructural level. As a suitable model system we use epitaxially grown films, which enable detailed static and dynamic studies. This package project combines expertise on both, magnetocaloric films and electrocaloric epitaxial films. We aim to describe the local structure with an adaptive concept, which we already successfully applied for isostructural magnetic shape memory alloys. We will expand this concept for the description of hysteretic losses during field cycling as it is postulated that such losses are closely connected to coarsening processes in the martensitic microstructure. In particular, the phase transformation, which leads to the caloric effects, will be studied with advanced local as well with integral probes in close collaboration with other participants in the SPP. Epitaxial heterostructures will be used to tune the strain in these materials, which allows modifying caloric properties. Similar approaches will be utilized to study multicaloric effects in heterostructures. From the direct comparison of electro- and magnetocaloric materials within this package project we expect a unified description of the underlying processes during ferroic cooling. Our fundamental studies will be accompanied by indirect and direct measurements to quantify the temperature change during a cooling cycle. The results of our fundamental investigations will enable us to identify the key parameters for more efficient ferroic cooling, which will be the basis for a further optimization of materials and device structures for potential applications.

需要更节能的制冷来减少当今生活方式对环境的影响。基于无扩散变换的固态制冷是一种有前途的解决方案。在我们的联合项目中，我们专注于表现出电热或磁热效应的材料，即施加电场或磁场会导致温度变化。此类材料以薄膜形式可用于微电子或微机械设备中的片上铁冷却。我们实验项目的主要目标是了解铁质冷却，特别是微观结构水平上的磁滞损耗。作为合适的模型系统，我们使用外延生长的薄膜，可以进行详细的静态和动态研究。该套件项目结合了磁热薄膜和电热外延薄膜的专业知识。我们的目标是用自适应概念来描述局部结构，我们已经成功地将其应用于同结构磁性形状记忆合金。我们将扩展这个概念来描述场循环期间的滞后损失，因为假设此类损失与马氏体微观结构中的粗化过程密切相关。特别是，将与 SPP 的其他参与者密切合作，利用先进的局部探针和积分探针来研究导致热量效应的相变。外延异质结构将用于调节这些材料的应变，从而可以改变热量特性。类似的方法将用于研究异质结构中的多热量效应。通过该封装项目中电热材料和磁热材料的直接比较，我们期望对铁冷却过程中的基础过程进行统一描述。我们的基础研究将伴随间接和直接测量，以量化冷却循环期间的温度变化。我们的基础研究结果将使我们能够确定更有效的铁冷却的关键参数，这将成为进一步优化潜在应用的材料和器件结构的基础。