Dimensionality, nanostructure, excitations and thermoelectric properties of Bi2Te3 and CoSb3 based nanomaterials

Bi2Te3和CoSb3(Skutterudite)基纳米材料将制备成纳米线、薄膜和纳米块体，研究维度、纳米结构对激发态和热电性能的影响。先进的合成方法包括脉冲电沉积法、分子束外延法和放电等离子烧结法。先进的表征方法包括能量过滤分析电子显微镜、高能X射线衍射、核非弹性散射和中子散射。热电性能的测量将在高达700K的宽温度范围内进行，控制二元化合物的化学计量比将为控制这些纳米材料中的电荷载流子密度提供基本的理解，并将产生优化的热电性能。纳米结构中的特定元素被发现限制了载流子的迁移率，其密度将得到优化。二元化合物的掺杂和合金化将被用来控制电荷载流子密度，也将被用来在Skutterudite类型的结构中引入填充原子。人工设计的结构将通过多层方法和三维缺陷结构来获得，以增加声子散射。该理论小组将在原子长度尺度上研究纳米结构对输运性质的影响。

Bi2Te3 and CoSb3 (skutterudite) based nanomaterials will be prepared as nanowires, thin films and nanostructured bulk to study the effects of dimensionality, nanostructure on excitations and thermoelectric properties. Advanced synthesis methods include potential-pulsed electrodeposition, molecular beam epitaxy and spark plasma sintering. Advanced characterization methods include energy-filtered analytical transmission electron microscopy, high-energy X-ray diffraction, nuclear inelastic scattering and neutron scattering. Thermoelectric properties will be measured over a wide temperature range up to 700 K. Controlled variation of stoichiometry of binary compounds will yield a fundamental understanding for controlling charge carrier densities in these nanomaterials and will yield optimized thermoelectric properties. Specific elements of the nanostructure were found to limit charge carrier mobilities and their density will be optimized. Doping and alloying of binary compounds will be used to control charge carrier densities but also to introduce filler atoms in skutterudite-type structures. Artificially designed structures will be obtained by a multilayer approach and by three dimensional defect structures for increasing phonon scattering. The theory group will investigate the effects of nanostructures on transport properties on the atomic length scale.