Understanding size and interface dependent anisotropic thermal conduction in correlated multilayer structures

了解相关多层结构中尺寸和界面相关的各向异性热传导

• 批准号: 122637388
• 负责人: Professor Dr. Peter E. Blöchl
• 金额: --
• 依托单位: Institut für Materialphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/122637388?language=en
• 关键词: Understanding; size; interface; dependent; anisotropic

It has recently been established that a very effective method for enhancement of thermoelectric efficiency is through suppression of thermal conductivity by structuring at the nanoscale, such as in multilayer systems. However, the mechanisms of this effect, i.e. the scattering and blocking of phonons at various wavelengths by interfaces are not well understood. The objective of this proposed joint project is to further develop the understanding of anisotropic and size dependent thermal conduction in oxide multilayer systems. We have optimized the 3-omega method in top and bottom electrode geometries for reliable measurements of thermal conductivity κ. The use of neural networks in combination with detailed finite element modelling of the coupled thermal and electrical conditions will allow for high-precision determination of in-plane and cross-plane contributions, κ┴ and κ||. Our continuum modelling of phonon dispersion has led to the selection of promising thermoelectric oxide systems for multilayers, namely doped SrTiO3 and Pr1-xCaxMnO3 and the misfit layered compound Ca3Co4O9, for our further studies. Separating out the influence of acoustic impedance mismatch of layers from various scattering contributions of interfaces, disorder, and dopants will be performed by careful experimental studies combined with atomic level modelling of thermal conductivity using non-equilibrium molecular dynamics and the phonon Boltzmann equation.

最近已经确定，提高热电效率的一种非常有效的方法是通过纳米级结构（例如多层系统）来抑制热导率。然而，这种效应的机制，即界面对不同波长的声子的散射和阻挡，尚不清楚。该联合项目的目标是进一步加深对氧化物多层系统中各向异性和尺寸相关热传导的理解。我们优化了顶部和底部电极几何形状的 3-omega 方法，以实现可靠的热导率 κ 测量。神经网络与耦合热电条件的详细有限元建模相结合，将能够高精度确定面内和跨面贡献 κ┴ 和 κ||。我们对声子色散的连续介质建模为我们的进一步研究选择了有前景的多层热电氧化物系统，即掺杂的 SrTiO3 和 Pr1-xCaxMnO3 以及失配的层状化合物 Ca3Co4O9。通过仔细的实验​​研究，结合使用非平衡分子动力学和声子玻尔兹曼方程的热导率原子级建模，将层的声阻抗失配的影响与界面、无序和掺杂剂的各种散射贡献分开。