基于界面原子混合的材料导热性能

Thermal conductivity of materials based on interfacial atomic mixing

构造了界面具有原子混合的硅锗(Si/Ge)单界面和超晶格结构.采用非平衡分子动力学模拟研究了界面原子混合对于单界面和超晶格结构热导率的影响,重点研究了界面原子混合层数、环境温度、体系总长以及周期长度对不同晶格结构热导率的影响.结果表明:由于声子的“桥接”机制,2层和4层界面原子混合能提高单一界面和少周期数的超晶格的热导率,但是在多周期体系中,具有原子混合时的热导率要低于完美界面时的热导率;界面原子混合会破坏超晶格中声子的相干性输运,一定程度引起热导率降低;完美界面超晶格具有明显的温度效应,而具有原子混合的超晶格热导率对温度的敏感性较低.

The Si/Ge single interface and superlattice structure with atom mixing interfaces are constructed.The effects of inter facial atomic mixing on thermal conductivity of single interface and super lattice structures are studied by non-equilibrium molecular dynamics simulation.The effects of the number of atomic mixing layers,temperature,total length of the system and period length on the thermal conductivity for different lattice structures are studied.The results show that the mixing of two and four layers of atoms can improve the thermal conductivity of Si/Ge lattice with single interface and the few-period superlattice due to the"phonon bridging"mechanism.When the total length of the system is large,the thermal conductivity of the super lattice with atomic mixing interfaces decreases significantly compared with that of the perfect interface.The interfacial atom mixing will destroy the phonon coherent transport in the super lattice and reduce the thermal conductivity to some extent.The superlattce with perfect interface has obvious temperature effect,while the thermal conductivity of the super lattice with atomic mixing is less sensitive to temperature.