Electrocaloric multilayer cooling device concepts

铁性冷却利用了固态材料相变附近的电场驱动的熵变化。它被认为是一种特别节能和环保的冷却技术。由于电能无处不在，特别是电热(EC)冷却效应似乎最有可能在未来的日常设备中使用。第一个资助期的理论研究清楚地表明，EC冷却装置的材料应该是弛豫型的，它应该按化学计量组成，致密和无间隙，以施加高电场强度，并且它应该非常薄。弛豫薄膜最大限度地满足了这些要求。因此，我们继续研究BaTiO_3基材料，这种材料是一种环保的无铅材料，可以实现如此高的电场。尤其是(Ba，Sc，Ca)(Ti，Zr)O_3：Mn和(Ba，Sc，Ca)(Ti，Sn)O_3：Mn，由于它们在较宽的温度范围内表现出较大的电致发光活性，因此仍然是我们工作的重点。我们通过多靶溅射来轻松地调整这些薄膜的成分，其中每个靶的功率是单独控制的。此外，多靶溅射使大规模生产能够在硬质和柔性衬底上以及卷筒到卷筒沉积。尤其是，第二个资助期的提案侧重于材料开发和优化、具有嵌入电极的多层叠层的制造和评估、多层EC冷却装置的概念以及EC冷却演示器的制造和评估。

Ferroic cooling exploits electric field-driven entropy changes near phase transitions in solid-state materials. It is considered an exceptionally energy-efficient and environmentally friendly cooling technology. Since electrical energy is ubiquitously available, in particular the electrocaloric (EC) cooling effect seems to have the highest potential for being used in future everyday devices.Theoretical studies in the first funding period have clearly shown that the material for EC cooling devices should make be of relaxor-type, that it should be composed stoichiometrically, dense and poreless to apply high electric field strengths and that it should be very thin. Relaxor thin films meet these requirements at the best.For that reason, we continue to study BaTiO3-based materials which are environmentally friendly lead-free materials allowing such high electric fields. In particular, (Ba,Sc,Ca)(Ti,Zr)O3:Mn and (Ba,Sc,Ca)(Ti,Sn)O3:Mn remain in the focus of our work because they show large EC activity in a broad temperature range. We adjust the composition of these thin films easily by multi-target sputtering where the power of each target is controlled separately. Furthermore, multi-target sputtering enables large-scale production on stiff and on flexible substrates as well as reel-to-reel deposition.In particular, the proposal for the second funding period focuses on material development and optimization, on fabrication and evaluation of multilayer stacks with embedded electrodes, on the concept of multilayer EC cooling devices and on the fabrication and evaluation of an EC cooling demonstrators.