Zinc oxide(ZnO)shows great potential in electronics,but its large intrinsic thermal conductivity limits its thermoelectric applications.In this work,we explore the significant carrier transport capacity and diameter-d...Zinc oxide(ZnO)shows great potential in electronics,but its large intrinsic thermal conductivity limits its thermoelectric applications.In this work,we explore the significant carrier transport capacity and diameter-dependent thermoelectric characteristics of wurtzite-ZnO(0001)nanowires based on first-principles and molecular dynamics simulations.Under the synergistic effect of band degeneracy and weak phonon-electron scattering,P-type(ZnO)_(73) nanowires achieve an ultrahigh power factor above 1500μW·cm^(-1)·K^(-2)over a wide temperature range.The lattice thermal conductivity and carrier transport properties of ZnO nanowires exhibit a strong diameter size dependence.When the ZnO nanowire diameter exceeds 12.72A,the carrier transport properties increase significantly,while the thermal conductivity shows a slight increase with the diameter size,resulting in a ZT value of up to 6.4 at 700 K for P-type(ZnO)_(73).For the first time,the size effect is also illustrated by introducing two geometrical configurations of the ZnO nanowires.This work theoretically depicts the size optimization strategy for the thermoelectric conversion of ZnO nanowires.展开更多
Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly ...Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly been studied,whereas the in-plane thermal conductivity has received less attention due to their limited thickness.展开更多
文摘为提高星载电子器件热分析的模拟分辨率和精度以及被动热控装置的控温效果,本文建立系统多尺度模型获得不同尺度下卫星内部电子器件的温度场和热流信息.结果表明:系统多尺度模型在系统级尺度模拟精度与实际模型相对误差小于9%,并且可消耗较少的计算资源获得器件级尺度芯片微小结构的热信息.系统级模型可从宏观尺度评估星载被动热控材料的控温隔热性能,采用复合相变隔热材料可将载荷舱室温度波动幅值降至2.43 K,相比平台舱室温度波动幅值降低约69.43%,通过复合相变隔热材料隔热后的温度波动信号呈现向高频域部分转移的特征.基于多元回归分析选定需要进行重点隔热控温的舱室后,采用器件级简化模型得到不同热控装置布局下的温度场信息形成训练数据集,采用神经网络遗传算法在器件尺度预测被动热控装置的最佳安装位置,并得到减小器件最大温度波动的热控布局方案,最大温度波动降低2.74 K.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52130604 and 51825604)。
文摘Zinc oxide(ZnO)shows great potential in electronics,but its large intrinsic thermal conductivity limits its thermoelectric applications.In this work,we explore the significant carrier transport capacity and diameter-dependent thermoelectric characteristics of wurtzite-ZnO(0001)nanowires based on first-principles and molecular dynamics simulations.Under the synergistic effect of band degeneracy and weak phonon-electron scattering,P-type(ZnO)_(73) nanowires achieve an ultrahigh power factor above 1500μW·cm^(-1)·K^(-2)over a wide temperature range.The lattice thermal conductivity and carrier transport properties of ZnO nanowires exhibit a strong diameter size dependence.When the ZnO nanowire diameter exceeds 12.72A,the carrier transport properties increase significantly,while the thermal conductivity shows a slight increase with the diameter size,resulting in a ZT value of up to 6.4 at 700 K for P-type(ZnO)_(73).For the first time,the size effect is also illustrated by introducing two geometrical configurations of the ZnO nanowires.This work theoretically depicts the size optimization strategy for the thermoelectric conversion of ZnO nanowires.
基金supported by the National Natural Science Foundation of China(Grant Nos.52276086 and 52130604)the Basic Research Program of China(Grant No.514010303-102)the K.C.Wong Education Foundation。
文摘Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly been studied,whereas the in-plane thermal conductivity has received less attention due to their limited thickness.
