Study On Thermal Transport Of Van Der Waals Phosphorus Nanotube Array

The thermal transport characteristics have been a frontier subject in the field of physics and materials research,especially the exploration of the thermal transport phenomenon of micro nano materials,which is of great research value and important application significance.The research on the thermal transport characteristics of materials can help solve many basic problems that are perplexing the world today.For example,finding new effective and efficient heat dissipation material help solve thermal gathered in electronic devices,the design and manufacture more excellent thermoelectric devices to help alleviate energy shortage,the development of new type of heat flow control devices help to optimize the heat control.In recent years,new phosphorous nanotubes have been successfully prepared.Considering the excellent physical properties and unique geometry of phosphorous materials and their potential applications in the field of micro nano electronic devices,we have systematically studied the thermal transport characteristics of several typical types of van der Waals arrays.The research content of this paper is expected to provide theoretical guidance for the design and preparation of new devices based on phosphorus nanotubes.This paper mainly includes the following work:1.By combining first-principles calculations with the Boltzmann transport equation,we systematically investigate the thermal transport properties of two-dimensional phosphorus nanotube arrays（PNTA）.The results show that PNTA has high lattice thermal conductivity.At room temperature,the average lattice thermal conductivity of PNTA is close to 260 W/m K,which is much higher than that of black phosphorene and blue phosphorrene.More interestingly,PNTA exhibits isotropic heat transport properties contrary to its anisotropic geometry.By calculating and comparing the key factors affecting thermal transport,we find that the weak phonon anharmonic and scattering intensity of PNTA lead to high lattice thermal conductivity.The anomalous isotropic lattice thermal conductivity is mainly derived from similar phonon group velocities and cut-off frequencies in two directions.Finally,through in-depth analysis of the interaction between atoms,the causes of this isotropic heat transport phenomenon are explained.This work will help us to deepen our understanding of the isotropic/anisotropic heat transport of materials and provide theoretical guidance for thermal management applications.2.Thermal transport,electron transport,and thermoelectric properties of MP₁₅（M=K,Na）are studied by first-principles calculation and Boltzmann transport equation.The results show that MP₁₅ is an indirect bandgap semiconductor with high carrier mobility.Its inherent characteristics in phonon transport significantly inhibit the phonon heat transport of MP₁₅,resulting in low intrinsic lattice thermal conductivity.At room temperature,the interlaminar lattice thermal conductivity is only 0.65～0.96 W/m K.On the other hand,the electron transport coefficient along the interlayer direction of MP₁₅has a good performance under the condition of n-type doping.And because of the geometric anisotropy,the lattice thermal conductivity and electron transport coefficient is also different in all directions.Finally,combining the two aspects of heat transport and electric transport coefficient,we calculated the thermoelectric quality factor ZT value of MP₁₅.The results show that the MP₁₅ block has good thermoelectric properties,and the maximum ZT value can reach 2.09 at700K,which indicates that the MP₁₅ block is a potential anisotropic thermoelectric material.Our findings will lead to further experimental exploration of similar phosphorus nanotube arrays and layered materials in thermoelectric devices.