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The continuous upgrading of electronic technology has facilitated the integration and miniaturization of electronic and electrical equipment, as well as putting great pressure on the multifunctional demand for internal materials. Developing insulating materials with both low permittivity and high thermal conductivity has become imperative. This perspective focuses on polyimide (PI), which is the top material of the polymer material pyramid, discusses the characteristic parameters that affect its dielectric property and thermal conductivity. A series of basic schemes to regulate the dielectric/thermal properties of PI are summarized, revealing the bottlenecks and drawbacks of the current research. Future development trends of PIs featured low permittivity-high thermal conductivity are anticipated, and novel ideas are proposed for the development of new generation of multifunctional PIs. [ABSTRACT FROM AUTHOR]

Conventional techniques of measuring thermal transport properties may be unreliable or unwieldy when applied to nanostructures. However, a simple, all-electrical technique is available for all samples featuring high-aspect-ratio: the 3 ω method. Nonetheless, its usual formulation relies on simple analytical results which may break down in real experimental conditions. In this work we clarify these limits and quantify them via adimensional numbers and present a more accurate, numerical solution to the 3 ω problem based on the Finite Element Method (FEM). Finally, we present a comparison of the two methods on experimental datasets from InAsSb nanostructures with different thermal transport properties, to stress the crucial need of a FEM counterpart to 3 ω measurements in nanostructures with low thermal conductivity. [ABSTRACT FROM AUTHOR]

Micro/nano electronic devices heat dissipation depends heavily on the thermal interface materials (TIMs). Despite notable progress, it is hard to efficaciously enhance the thermal properties of the hybrid TIMs with high-load additives due to an absence of effective heat transfer routes. Herein, the low content of three-dimensional (3D) graphene with interconnected networks is adopted as the additive to improve the thermal properties of epoxy composite TIMs. The thermal diffusivity and thermal conductivity of the as-prepared hybrids were dramatically improved by constructing thermal conduction networks after adding 3D graphene as fillers. The 3D graphene/epoxy hybrid's optimal thermal characteristics were observed at 1.5 wt% of 3D graphene content, corresponding to a maximum enhancement of 683%. Besides, heat transfer experiments were further performed to determine the superb heat dissipation potential of the 3D graphene/epoxy hybrids. Moreover, the 3D graphene/epoxy composite TIM was also applied to high-power LED to improve heat dissipation. It effectively reduced the maximum temperature from 79.8 °C to 74.3 °C. These results are beneficial for the better cooling performance of electronic devices and provide useful guidelines for advancing the next-generation TIMs. [ABSTRACT FROM AUTHOR]

The investigation of thermal transport is crucial to the thermal management of modern electronic devices. To obtain the thermal conductivity through solution of the Boltzmann transport equation, calculation of the anharmonic interatomic force constants has a high computational cost based on the current method of single-point density functional theory force calculation. The recent suggested machine learning interatomic potentials (MLIPs) method can avoid these huge computational demands. In this work, we study the thermal conductivity of two-dimensional MoS2-like hexagonal boron dichalcogenides (H-B2 VI 2; VI = S, Se, Te) with a combination of MLIPs and the phonon Boltzmann transport equation. The room-temperature thermal conductivity of H-B2S2 can reach up to 336 W⋅m−1⋅K−1, obviously larger than that of H-B2Se2 and H-B2Te2. This is mainly due to the difference in phonon group velocity. By substituting the different chalcogen elements in the second sublayer, H-B2 VIVI ′ have lower thermal conductivity than H-B2 VI 2. The room-temperature thermal conductivity of B2STe is only 11% of that of H-B2S2. This can be explained by comparing phonon group velocity and phonon relaxation time. The MLIP method is proved to be an efficient method for studying the thermal conductivity of materials, and H-B2S2-based nanodevices have excellent thermal conduction. [ABSTRACT FROM AUTHOR]

This paper reports an enhancement of the nonlinear conductivity, thermal and mechanical properties of micro-silicon carbide/silicone elastomer (m-SiC/SE) composites by adding nano-aluminum nitride (n-AlN) for power module encapsulation applications. The electrical properties (such as nonlinear conductivity characteristics and transient permittivity obtained from polarization current, and trap distributions obtained from thermally stimulated depolarization current) and material properties (including thermo-gravimetric analysis, coefficient of thermal expansion (CTE), and thermal conductivity, tensile strength, strain at break and Young’s modulus) of the pure SE, m-SiC/SE microcomposites, m-SiC/n-AlN/SE hybrid composites are investigated. The effect of the m-SiC fillers and n-AlN fillers on physicochemical properties of the SE matrix is analyzed by FT-IR spectroscopy and crosslinking degree. The measured nonlinear conductivity and transient permittivity are used for electric field simulation under DC stationary and square voltages. It is found that the addition of n-AlN fillers in the SE hybrid composite improves the nonlinear conductivity characteristics and mitigates the electric field under DC stationary and square voltages, compared to the SE microcomposite. Furthermore, the m-SiC/n-AlN/SE hybrid composite has a higher thermal degradation temperature, thermal conductivity, tensile strength, Young’s modulus, and crosslinking degree than the SE microcomposite, whereas their CTE and strain at break are lower. It is elucidated that the m-SiC/n-AlN/SE hybrid composite with enhanced nonlinear conductivity and material properties is a promising packaging material for high-voltage power modules. [ABSTRACT FROM AUTHOR]

Thermal conductivity of porous graphene can be affected by defect concentration, nanopore shape and distribution, and it is hard to clarify the effects due to the correlation of those factors. In this work, molecular dynamics simulation is used to compare the thermal conductivity of graphene with three shapes of regularly arranged nanopores. The results prove the dominant role of defect concentration under certain circumstances in reducing thermal conductivity, while the coupling effect of nanopore shape should be noticed. When the atoms at the local phonon scattering area around each nanopore are properly removed, the abnormal increment of thermal conductivity can be detected with the increase of defect concentration. Heat flux vector angles can effectively characterize the local phonon scattering area, which can be used to describe the effect of nanopore shape. The coupling effect of defect concentration and pore shape with similar heat flux path is clarified according to this process. By adjusting vertex angle of triangle defect, there is a balanced state of the effect factors between the variation of defect concentration and the same phonon scattering area. It provides a possible way to describe the weighing factors of the coupling effect. The results suggest a feasible approach to optimize and regulate thermal properties of porous graphene in nanodevice. [ABSTRACT FROM AUTHOR]

Recognizing high performance thermoelectric (TE) ceramics is challenging due to high thermal conductivity and interdependent electrical and thermal transport properties. Herein we report the strategy of isovalent Al substitution in LaCoO3, which resulted in the enhancement of electrical conductivity by band engineering and increased charge carrier mobility via effective mass and Fermi energy optimization. The Al substitution in LaCoO3 not only enhances the electrical transport properties but also decrease the lattice thermal conductivity through enhanced phonon scattering originated from the lattice strain induced by huge mass fluctuation of Co and substituted Al atom. The results indicate that the electrical conductivity increase with increasing the Al substitution and the maximum value of 642 S cmâˆ'1 was observed at 753 K and the maximum power factor (73.3 µ W mâˆ'1Kâˆ'2) was achieved at 703 K for the sample LaCo0.97Al0.03O3. The Al-substitution enhanced the charge carrier mobility from 0.21 cm2 Vâˆ'1 sâˆ'1 to 51.6 cm2 Vâˆ'1 sâˆ'1 by decreasing the effective mass from 28.76*me to 12.76*me. The decreased carrier concentration with Al substitution is due to the upward shift of Fermi energy towards the conduction band. The lowest thermal conductivity value (0.87 W mâˆ'1Kâˆ'1) was obtained at 303 K for the sample LaCo0.95Al0.05O3. The lattice thermal conductivity of LaCo0.95Al0.05O3 (1.259 W mâˆ'1Kâˆ'1) was reduced about 48% when compared with pure LaCoO3 (2.437 W mâˆ'1Kâˆ'1) at 753 K. The present work reveals the importance of decoupling the electrical and thermal transport properties in achieving high performance TE ceramics. [ABSTRACT FROM AUTHOR]

Motivated by recent progress in the two-dimensional (2D) materials of group VI elements and their experimental fabrication, we have investigated the stability, optoelectronic and thermal properties of Janus α -Te2S monolayer using first-principles calculations. The phonon dispersion and MD simulations confirm its dynamical and thermal stability. The moderate band gap (∼1.5 eV), ultrahigh carrier mobility (∼103 cm2 Vâˆ'1 sâˆ'1), small exciton binding energy (0.26 eV), broad optical absorption range and charge carrier separation ability due to potential difference (Î" V  = 1.07 eV) on two surfaces of Janus α -Te2S monolayer makes it a promising candidate for solar energy conversion. We propose various type-II heterostructures consisting of Janus α -Te2S and other transition metal dichalcogenides for solar cell applications. The calculated power conversion efficiencies of the proposed heterostructures, i.e. α -Te2S/T-PdS2, α -Te2S/BP and α -Te2S/H-MoS2 are ∼21%, ∼19% and 18%, respectively. Also, the ultralow value of lattice thermal conductivity (1.16 W mâˆ'1 Kâˆ'1) of Janus α -Te2S makes it a promising material for the fabrication of next-generation thermal energy conversion devices. [ABSTRACT FROM AUTHOR]

Of late, atomically thin two-dimensional zinc-sulfide (2D-ZnS) shows great potential for advanced nanodevices and as a substitute to graphene and transition metal di-chalcogenides owing to its exceptional optical and electronic properties. However, the functional performance of nanodevices significantly depends on the effective heat management of the system. In this paper, we explored the thermal transport properties of 2D-ZnS through molecular dynamics simulations. The impact of length, temperature, and vacancy defects on the thermal properties of 2D-ZnS are systematically investigated. We found that the thermal conductivity (TC) rises monotonically with increasing sheet length, and the bulk TC of ∼30.67 W mK−1 is explored for an infinite length ZnS. Beyond room temperature (300 K), the TC differs from the usual 1/T rule and displays an abnormal, slowly declining behavior. The point vacancy (PV) shows the largest decrease in TC compared to the bi vacancy (BV) defects. We calculated phonon modes for various lengths, temperatures, and vacancies to elucidate the TC variation. Conversely, quantum corrections are used to avoid phonon modes' icing effects on the TC at low temperatures. The obtained phonon density of states (PDOS) shows a softening and shrinking nature with increasing temperature, which is responsible for the anomaly in the TC at high temperatures. Owing to the increase of vacancy concentration, the PDOS peaks exhibit a decrease for both types of defects. Moreover, the variation of the specific heat capacity and entropy with BV and PV signify our findings of 2D-ZnS TC at diverse concentrations along with the different forms of vacancies. The results elucidated in this study will be a guide for efficient heat management of ZnS-based optoelectronic and nano-electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, the structural stability, electronic, optical, mechanical, and thermal properties of diphenylacetylene-based graphyne (DPAG) nanosheet are investigated using first-principle calculations based on density functional theory (DFT). The absolute value of the calculated cohesive energy reveals that DPAG nanosheet is a structurally stable two-dimensional material. Also, in the results of phononic dispersion curves, the absence of imaginary frequencies confirms the dynamic stability of this novel material. In addition, the theoretical electronic band structure and density of states reveal the semiconducting nature of DPAG nanosheet. The optical analysis shows that the first absorption peaks of the imaginary and real parts of dielectric constants along the in-plane and out-of-plane polarizations of DPAG monolayer occur in the visible range of the electromagnetic spectrum. On the other hand, the DPAG nanosheet exhibits orthotropic elastic behavior with four independent constants comparable with the data of similar materials available in the literature. Moreover, DFT calculations of the lattice thermal conductivity of DPAG reveals an anomalously very low thermal conductivity of this nanosheet showing its perfect thermal non-conductivity. Our results provide deep insights into the potential applications of DPAG nanosheet for the design of new optoelectronic/nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Two different integration technologies of GaN-on-diamond are explored, direct growth of polycrystalline diamond (PCD) on GaN (sample A) and deposition of GaN on PCD (sample B). The reversed evolution of PCD grain structure is assumed for each technology, resulting in an increasing/decreasing tendency of thermal conductivity with growth thickness. Simulation of AlGaN/GaN high electron mobility transistors on PCD substrate with capped diamond is made considering anisotropic and inhomogeneous thermal conductivities of GaN and PCD, different combinations of thermal boundary resistance (TBR) values at the top diamond/GaN and bottom GaN/PCD substrate are investigated. The results show that the effect of top TBR is limited and increasing the bottom TBR from 6.5 to 100 m2K GW−1 results in a temperature rise of 80.8 °C for sample A and 85.3 °C for sample B at power dissipation of 10 W mm−1. Enlarging the thickness of capped diamond helps to reduce the junction temperature, which is more effective at small top TBR under constant bottom TBR and at large bottom TBR with fixed top TBR. In addition, increasing gate pitch is a promising solution to reduce junction temperature and a weak dependence of junction temperature on gate width is revealed. [ABSTRACT FROM AUTHOR]

Details of an experimental set-up and an evaluation method for determining temperature dependent thermal conductivities from one-dimensional steady-state temperature distributions are presented. The method is validated by obtaining continuous values for the thermal conductivities of pure Ni in the temperature range between 440 K and 740 K, brass (Cu-30Zn) in the temperature range between 350 K and 650 K and a titanium aluminide (TiAl-TNM) in the temperature range between 400 K and 700 K. The results are in agreement with available literature data. The reported scatter in the literature on conductivities is caused by microstructural or/and compositional differences, which highlights the necessity for swift and accurate experimental determination of thermal properties. For this, the proposed temperature gradient evaluation method is especially suited as it allows the direct determination of thermal properties within large temperature intervals using only a single experimental run. The experimental effort for a comprehensive study of a material is thus drastically reduced as compared to the conventional method of determining thermal conductivity from measured thermal diffusivities and heat capacities. The experimental set-up additionally allows the independent determination of thermal diffusivity as function of temperature. No prior knowledge of any material properties of a given sample is necessary. [ABSTRACT FROM AUTHOR]

Unlike tremendous works on the electronic structures of tetradymite compounds, studies of their thermal properties are relatively rare. Here, first-principles calculations and Boltzmann theory are combined to investigate the phonon transport of such kind of layered materials. Using four binary tetradymites as prototypical examples, it is interesting to find that the weak van der Waals (vdW) interactions play an important role in determining their lattice thermal conductivities, which are obviously higher than those without the consideration of vdW, especially for the out-of-plane direction. In principle, such enhanced phonon transport can be attributed to the decreased interlayer spacing caused by the presence of vdW, which effectively reduces the strong anharmonicity of the systems. Indeed, we observe relatively smaller Grüneisen parameter together with larger phonon group velocity and relaxation time. Our theoretical work demonstrates the vital importance of the seemingly weak vdW forces in predicting the phonon transport properties of various layered structures. [ABSTRACT FROM AUTHOR]

A nanostructured n-type Bi2Te2.7Se0.3 (BTS) alloy with a unique microstructure was prepared using a facile melting-rotation-quenching process followed by ball-milling and uniaxial hot-press sintering at 623 K. Anisotropy in the resulting microstructure showed anisotropic electrical and thermal transport properties in two directions normal to the pressing axis. The texture of the nanostructured BTS alloy was analyzed by x-ray diffraction and scanning electron microscopy. Based on the geometric phase analysis of a high resolution transmission electron microscopy images, abundant dislocations, high grain boundary density, and oxide impurity were identified, which act as phonon scattering centers. Higher anisotropy in thermal conductivity combined with oxide impurity resulted in an ultra-low phonon thermal conductivity of ∼0.305 W mK−1 at 423 K in the nanostructured n-type BTS in the direction parallel to the pressing axis. Laser power- and temperature-dependent Raman spectra analyses provided a deeper insight into the anisotropy in thermal transport properties. Optimum power factor and low thermal conductivity, due to the combination of grain alignment and oxide impurity, resulted in a dimensionless figure of merit (zT) value of ∼0.75 at 423 K. In comparison, the high and opposite temperature dependences of electrical conductivity and thermal conductivity led to a better average zT value of ∼0.68 and a thermoelectric energy conversion efficiency percentage of ∼4.4% in the operating temperature range (300–423 K) in the direction parallel to the pressing axis. [ABSTRACT FROM AUTHOR]

The thermal properties of individual single-walled carbon nanotubes (SWCNTs) have been well documented in the literature following decades of intensive study. However, when SWCNTs form a macroscale assembly, the thermal transport in these complex structures usually not only depends on the properties of the individual tubes, but also is affected and sometimes dominated by inner structural details, e.g. bundles and junctions. In this work, we first performed an experimental measurement of the thermal conductivities of individual SWCNT bundles of different sizes using a suspended micro-thermometer. The results, together with the data that we obtained from a previous work, give a complete experimental understanding of the effect of bundling on the thermal conductivity of SWCNTs. With these quantitative understandings, we propose a phenomenological model to describe the thermal transport in two-dimensional (2D) SWCNT films. The term 'line density' is defined to describe the effective thermal transport channels in this complex 2D network. Along with experimentally obtained geometric statistics and film transparency, the thermal conductance of SWCNTs is estimated, and the effects of bundle length, diameter, and contact conductance are systematically discussed. Finally, we extend this model to explain thermal transport in 2D networks of one-dimensional van der Waals heterostructures, which are coaxial hetero-nanotubes we recently synthesized using SWCNTs as the template. This extended model suggests that the contribution of boron nitride nanotubes (BNNTs) to the overall performance of a SWCNT–BNNT heterostructured film depends on the transparency of the original SWCNT film. The increase in the thermal conductance of a highly transparent film is estimated to be larger than that of a less transparent film, which shows a good agreement with our experimental observations and proves the validity of the proposed phenomenological model. [ABSTRACT FROM AUTHOR]

High thermal conductivity is an important parameter for nitride-based power electronic and deep-UV light emitters. Especially in the latter case short period superlattices and multicomponent alloys are used and the knowledge of the thermal properties of the binary compounds is sufficient. In-plane and cross-plane thermal conductivity of AlGaN/GaN superlattices were measured by differential two-wire 3ω method in the temperature range from 147 to 325 K. Samples were grown by metalorganic vapor phase epitaxy; the structure quality and accuracy of superlattice structures preparation were verified by means of HRXRD and transmission electron microscopy. It was observed, that value of thermal conductivities decrease with decreasing period thickness, while temperature dependencies differ from each other—in-plane thermal conductivity decreases, and cross-plane—increases with increasing temperature. Callaway method was used for thermal conductivity calculation; dependence of boundary scattering rate on the phonon wavelength was taken into account. Minimum thermal conductivity was added to calculated values to include the influence of high frequency acoustic phonons and optical phonons on the heat transport. Calculations are in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Currently, it is still unclear how and to what extent a change in temperature impacts the relative contributions of coherent and incoherent phonons to thermal transport in superlattices. Some seemingly conflicting computational and experimental observations of the temperature dependence of lattice thermal conductivity make the coherent–incoherent thermal transport behaviors in superlattices even more elusive. In this work, we demonstrate that incoherent phonon contribution to thermal transport in superlattices increases as the temperature increases due to elevated inelastic interfacial transmission. On the other hand, the coherent phonon contribution decreases at higher temperatures due to elevated anharmonic scattering. The competition between these two conflicting mechanisms can lead to different trends of lattice thermal conductivity as temperature increases, i.e. increasing, decreasing, or non-monotonic. Finally, we demonstrate that the neural network-based machine learning model can well capture the coherent–incoherent transition of lattice thermal transport in the superlattice, which can greatly aid the understanding and optimization of thermal transport properties of superlattices. [ABSTRACT FROM AUTHOR]

Generally speaking, for materials with the same structure, the thermal conductivity is higher for lighter atomic masses. However, we found that the thermal conductivity of CaO is lower than that of CaS, despite the lighter atomic mass of O than S. To uncover the underlying physical mechanisms, the thermal conductivity of CaM (M = O, S, Se, Te) and the corresponding response to strain is investigated by performing first-principles calculations along with the phonon Boltzmann transport equation. For unstrained system, the order of thermal conductivity is CaS > CaO > CaSe > CaTe. This order remains unchanged in the strain range of −2% to 5%. When the compressive strain is larger than 2%, the thermal conductivity of CaO surpasses that of CaS and becomes the highest thermal conductivity material among the four compounds. By analyzing the mode-dependent phonon properties, the phonon lifetime is found to be dominant over other influential factors and leads to the disparate response of thermal conductivity under strain. Moreover, the changing trend of three-phonon scattering phase space is consistent with that of phonon lifetime, which is directly correlated to the phonon frequency gap induced by the LO-TO splitting. The variation of Born effective charge is found to be opposite for CaM. The Born effective charge of CaO decreases with tensile strain increasing, demonstrating stronger charge delocalization and lower ionicity, while the Born effective charges of CaS, CaSe, and CaTe show a dramatic increase. Such variation indicates that the bonding nature can be effectively tuned by external strain, thus affecting the phonon anharmonic properties and thermal conductivity. The difference of bonding nature is further confirmed by the band structure. Our results show that the bonding nature of CaM can be modulated by external strain and leads to disparate strain dependent thermal conductivity. [ABSTRACT FROM AUTHOR]

Low dimensional systems, nanowires (NWs), in particular, have exhibited excellent optical and electronic properties. Understanding the thermal properties in semiconductor NWs is very important for their applications in electronic devices. In the present study, the thermal conductivity of a freestanding silicon NW is estimated by employing Raman spectroscopy. The advantage of this technique is that the excitation source (laser) acts as both the heater and probe. The variations of the first-order Raman peak position of the freestanding silicon NW with respect to temperature and laser power are recorded. From the analysis of effective laser power absorbed by exposed silicon NW and a detailed Raman study along with the concept of longitudinal heat distribution in silicon NW, the thermal conductivity of the freestanding silicon NW of ∼112 nm diameter is estimated to be ∼53 W m−1 K− 1. [ABSTRACT FROM AUTHOR]

Thermal management is one of the key challenges in nanoelectronic and optoelectronic devices. The development of a van der Waals heterostructure (vdWH) using the vertical positioning of different two-dimensional (2D) materials has recently appeared as a promising way of attaining desirable electrical, optical, and thermal properties. Here, we explore the lateral and flexural thermal conductivity of stanene/2D-SiC vdWH utilizing the reverse non-equilibrium molecular dynamics simulation and transient pump-probe technique. The effects of length, area, coupling strength and temperature on the thermal transport are studied systematically. The projected lateral thermal conductivity of a stanene/2D-SiC hetero-bilayer is found to be 66.67 , which is greater than stanene, silicene, germanene, MoSe2 and even higher than some hetero-bilayers, including MoS2/MoSe2 and stanene/silicene. The lateral thermal conductivity increases as the length increases, while it tends to decrease with increasing temperature. The computed flexural interfacial thermal resistance between stanene and 2D-SiC is 3.0622 K.m2 W−1, which is close to other 2D hetero-bilayers. The interfacial resistance between stanene and 2D-SiC is reduced by 70.49% and 50.118% as the temperature increases from 100 K to 600 K and the coupling factor increases from to , respectively. In addition, various phonon modes are evaluated to disclose the fundamental mechanisms of thermal transport in the lateral and flexural direction of the hetero-bilayer. These results are important in order to understand the heat transport phenomena of stanene/2D-SiC vdWH, which could be useful for enhancing their promising applications. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach for processing measured data from active Infra Red (IR) thermography, where a soft sensing algorithm is exploited for in depth defect reconstruction. This is achieved by propagating the information gathered at the wall surface to the inner layers. Correlating the experimental 2D measurements to a Finite Element (FE) model of the tested specimen it is possible to update the model with the measured data and change the geometry of the simulated inner defect, until the surface temperature distribution calculated corresponds to the measured one. Following that strategy, the unknown defect geometry can be determined. The method developed and presented in this paper consists of an optimization problem based on the minimization of the difference between the surface temperature distribution measured on the sample subjected to an active thermography test and the one resulting from the FE model. The optimization variables are the geometrical parameters (depth, width, thickness and position) characterizing the defect which will be fully determined at the complete convergence, within a given tolerance, of the optimization problem. The method includes also a preprocessing algorithm, based on the same experimental data and FE model, which allows to determine thermal and mechanical properties of the object under test, like surface emissivity, heat capacity and material conductivity and density, which are often unknown especially in the case of works of art. This soft-sensing procedure has been applied to a virtual experiment to estimate the accuracy of the reconstructed geometry and to a simulacrum of ancient fresco including defects realized on purpose. [ABSTRACT FROM AUTHOR]

Borophene allotropes have many unique physical properties due to their polymorphism and similarity between boron and carbon. In this work, based on the density functional theory and phonon Boltzmann transport equation, we investigate the lattice thermal conductivity κ of both β12 and χ3 borophene. Interestingly, these two allotropes with similar lattice structures have completely different thermal transport properties. β12 borophene has almost isotropic κ around 90 W/(m⋅K) at 300 K, while κ of χ3 borophene is much larger and highly anisotropic. The room temperature κ of χ3 borophene along the armchair direction is 512 W/(m⋅K), which is comparable to that of hexagonal boron nitride but much higher than most of the two-dimensional materials. The physical mechanisms responsible for such distinct thermal transport behavior are discussed based on the spectral phonon analysis. More interestingly, we uncover a unique one-dimensional transport feature of transverse acoustic phonon in χ3 borophene along the armchair direction, which results in a boost of phonon relaxation time and thus leads to the significant anisotropy and ultrahigh thermal conductivity in χ3 borophene. Our study suggests that χ3 borophene may have promising application in heat dissipation, and also provides novel insights for enhancing the thermal transport in two-dimensional systems. [ABSTRACT FROM AUTHOR]

Localization, one of the basic phenomena for wave transport, has been demonstrated to be an effective strategy to manipulate electronic, photonic, and acoustic properties of materials. Due to the wave nature of phonons, the tuning of thermal properties through phonon localization would also be expected, which is beneficial to many applications such as thermoelectrics, electronics, and phononics. With the development of nanotechnology, nanostructures with characteristic length about ten nanometers can give rise to phonon localization, which has attracted considerable attention in recent years. This review aims to summarize recent advances with theoretical, simulative, and experimental studies toward understanding, prediction, and utilization of phonon localization in disordered nanostructures, focuses on the effect of phonon localization on thermal conductivity. Based on previous researches, perspectives regarding further researches to clarify this hectic-investigated and immature topic and its exact effect on thermal transport are given. [ABSTRACT FROM AUTHOR]

This work aims to present a method for simultaneously estimating the thermal conductivity, k, and specific heat, cp, in samples of stainless steel 304 and cemented carbide by accounting the imperfect thermal contact at the heater–sample interface. A transient one-dimensional heat conduction model with constant thermal properties is used. The metallic sample is placed in the middle of a polyimide heater and a thermal insulator. A constant heat flux is applied on the specimen upside surface and a thermal insulation condition is maintained on the opposing surface, where a type T thermocouple measures the temperature response. Contact resistance is determined and accounted for as a reducing factor on heat flux. Instead of considering a lumped model, a microscopic approach of the contacting regions is used to describe both the surface roughness and the fluid gap. With the intention of guaranteeing simultaneous and reliable estimates for both thermal properties, sensitivity analysis is used to establish heat flux intensity, experiment duration, time step for data acquisition, and other characteristics of the experiments. To simultaneously achieve both thermal properties, the optimization method BFGS (Broyden–Fletcher–Goldfarb–Shanno) is employed to minimize a least-squares objective function comparing experientially measured and numerically calculated temperatures. The numerical solution for the transient conduction problem is determined with COMSOL, which solves the transient heat diffusion problem by discretizing it applying the finite element method (FEM). The linear system of equations is solved using the PARDISO solver and backward differentiation formula (BDF) method. Heat flux is estimated employing the sequential function specification method (SFSM) as a means of verifying the robustness of parameter estimation and experimental procedure. Moreover, uncertainty analysis is performed to confirm the quality of the results obtained. Finally, the uncertainty analysis outcomes and thermal properties estimated are compared with literature. [ABSTRACT FROM AUTHOR]

Monolayer beryllium oxide (BeO), a new graphene-like metal oxide material, has attracted tremendous interest since it was demonstrated to have high dynamic, thermal, kinetic and mechanical stabilities in recent years. This discovery enriches the catalogue of 2D materials and paves the way for the exploration of relevant properties. In this work, the electronic and thermal properties of monolayer BeO are predicted by first-principles calculations. Compared with graphene and monolayer hexagonal boron nitride (h-BN), the monolayer BeO is an insulator and its electrons are highly localized around O and Be atoms (ionic nature). More importantly, the thermal conductivity of monolayer BeO is found to be 266 Wm−1K−1 at 300 K, which is lower than that of graphene and h-BN but higher than most other 2D materials. Further spectrum analysis reveals that 75% of the thermal conductivity of monolayer BeO is contributed by phonons with a frequency from 0 to 5.4 THz. With the characteristics of wide bandgap and high thermal conductivity, monolayer BeO shows great potential for applications in electronic device packages and Li-ion batteries. [ABSTRACT FROM AUTHOR]

Using numerical simulations, we study the effects of magnetic resistivity and thermal conductivity in the dynamics and properties of solar jets with characteristics of Type II spicules and cool coronal jets. The dynamic evolution of the jets is governed by the resistive MHD equations with thermal conduction along the magnetic field lines on a 2.5D slice. The magnetic field configuration consists of two symmetric neighboring loops with opposite polarity, used to support reconnection and followed by the plasma jet formation. In total, 10 simulations were carried out with different values of resistivity and thermal conductivity that produce jets with different morphological and thermal properties we quantify. We find that an increase in magnetic resistivity does not produce significant effects on the morphology, velocity, and temperature of the jets. However, thermal conductivity affects both temperature and morphology of the jets. In particular, thermal conductivity causes jets to reach greater heights and increases the temperature of the jet-apex. Also, heat flux maps indicate the jet-apex and corona interchange energy more efficiently than the body of the jet. These results could potentially open a new avenue for plasma diagnostics in the Sun's atmosphere. [ABSTRACT FROM AUTHOR]

Unveiling the thermal transport properties of various one-dimensional (1D) or quasi-1D materials like nanowires, nanotubes, and nanorods is of great importance both theoretically and experimentally. The dimension or size dependence of thermal conductivity is crucial in understanding the phonon–phonon interaction in the low-dimensional systems. In this paper, we experimentally investigate the size-dependent thermal conductivity of individual single crystalline α-Fe2O3 nanowires collaborating the suspended thermal bridge method and the focused electron-beam self-heating technique, with the sample diameter (d) ranging from 180 nm to 661 nm and length (L) changing from 4.84 μm to 20.73 μm. An empirical relationship for diameter-/length-dependent thermal conductivity is obtained, which shows an approximately linear dependence on the aspect ratio (L/(1 + Cd)) at T = 300 K, where C is a fitting parameter. This is related to the boundary scattering and diameter effect of α-Fe2O3 nanowires although rigorous calculations are needed to confirm the result. [ABSTRACT FROM AUTHOR]

Nanofluids (Nfs) are considered as an effective working media in different thermal processes. Over the years, much attention has been paid to the problem of nanoparticle stability in base fluids in an unconfined area of research, especially in the field of thermal applications. There is still concern about the stability of nanoparticles and their effects on the transport properties and thermal performance in thermal systems. In the present paper, the transport properties and thermal behavior of ethylene glycol-water/ binary Nfs are investigated in two sections, considering the effect of particle stability and size growth. The first section covering the experimental work, which includes the preparation and characterization of the Nfs where different percentages of base fluids at different pH values are used for this purpose. The characterization of the Nfs explains the effect of the zeta potential on the particle size distribution and the hydrodynamic diameter of suspended particles. The second section involves the theoretical study, where the transport properties and thermal behavior of the Nfs are estimated taking into consideration the effect of the particle stability and size growth. It is found that the binary Nfs that contain different types of base fluids show different stability behavior at different pH values at the same particle concentration. Ethylene glycol-water/ binary Nfs at pH = 9 contain a low hydrodynamic diameter of suspended particles, and Nfs have good stability behavior. On the other hand, the Nfs at pH = 2 contain the maximum size of the particle hydrodynamic diameter. The Nfs that include 25% water + 75% ethylene glycol show a better stability behavior in comparison with other types of Nfs that included 75% water + 25% ethylene glycol. Particle size growth shows a significant effect on the transport properties (thermal conductivity and viscosity) as well as the particle-fluid interaction Nusselt number, Biot number, and convection heat transfer coefficient. [ABSTRACT FROM AUTHOR]

Polycrystalline BAsx (x = 0.80–1.10) compounds with different boron-to-arsenic elemental molar ratios were synthesized by a high-pressure and high-temperature sintering method. Compared with other ambient-pressure synthesis methods, high pressure can significantly promote the reaction speed as well as the reaction yield. As the content of arsenic increases from x = 0.91 to 1.10, the thermal conductivity of BAsx gradually increases from 53 to 65 W⋅m−1⋅K−1. Furthermore, the temperature dependence of thermal conductivities of these samples reveals an Umklapp scattering due to the increasing phonon population. This work provides a highly efficient method for polycrystalline BAs synthesis. [ABSTRACT FROM AUTHOR]

Polycrystalline BAsx (x = 0.80–1.10) compounds with different boron-to-arsenic elemental molar ratios were synthesized by a high-pressure and high-temperature sintering method. Compared with other ambient-pressure synthesis methods, high pressure can significantly promote the reaction speed as well as the reaction yield. As the content of arsenic increases from x = 0.91 to 1.10, the thermal conductivity of BAsx gradually increases from 53 to 65 W⋅m−1⋅K−1. Furthermore, the temperature dependence of thermal conductivities of these samples reveals an Umklapp scattering due to the increasing phonon population. This work provides a highly efficient method for polycrystalline BAs synthesis. [ABSTRACT FROM AUTHOR]

The transient plane source (TPS) method is a relatively newly developed transient approach for thermal conductivity measurement. Compared with the steady-state method, it is fast, and applicable to either solid, liquid or gas state materials; therefore, it has gained much popularity in recent years. However, during measurement, the measured power is influenced by the heat capacity of the electrical isolation films as well as the electrical resistance change of the metallic thin wire of the TPS probes. This further influences the measurement precision. Meanwhile, these two factors have been ignored in the traditional model of TPS developed by Gustafsson. In this paper, the influence of both the heat capacity and the resistance change of the TPS probe on the measured power is studied, and mathematical formulas relating the two factors and their respective corrections are deduced. Thereafter an improved model is suggested based on the traditional TPS model and the above theoretical models. Experiments on polymethylmethacrylate (PMMA) standard materials have been conducted using a home-made system, including TPS probes, data acquisition module and analysis software. The results show that the improved model can effectively improve the measurement precision of the TPS method by about 1.8–2.3% as evaluated by relative standard deviation. [ABSTRACT FROM AUTHOR]

The class of materials combining high electrical or thermal conductivity, optical transparency and flexibility is crucial for the development of many future electronic and optoelectronic devices. Silver nanowire networks show very promising results and represent a viable alternative to the commonly used, scarce and brittle indium tin oxide. The science and technology research of such networks are reviewed to provide a better understanding of the physical and chemical properties of this nanowire-based material while opening attractive new applications. [ABSTRACT FROM AUTHOR]

Thin films constituted of CuAlS2 nanoparticles deposited with various deposition velocities in single and multilayers onto silicon Si(111) substrates by thermal evaporation have been studied by lifting their structural and thermal properties. Thermal properties of Si(111) and Si(111)/CuAlS2 structures are determined by using the photothermal deflection technique by comparing experimental and theoretical signals. We succeed in extracting the thermal conductivity, the thermal diffusivity, and the electron free mean path of these deposited chalcogenide layers. For the multilayers, the obtained values of the thermal conductivity are in good agreement with the theoretical data. [ABSTRACT FROM AUTHOR]

In the present investigation, we report on the thermoelectric properties of PbSe0.5Te0.5: x (PbI2) from room temperature to 625 K. High-resolution transmission electron micrographs of the samples reveal endotaxial nanostructures embedded in a PbSe0.5Te0.5 matrix. The combined effect of mass fluctuation and nanostructures reduces the thermal conductivity to a great extent compared to PbTe and PbSe, without affecting the carrier mobility. As a result, a thermoelectric figure of merit with a value of 1.5 is achieved at 625 K. This value is significantly higher than that of the available state-of-the-art n-type materials. [ABSTRACT FROM AUTHOR]

DNA has a well-defined structural transition--the denaturation of its double-stranded form into two single strands--that strongly affects its thermal transport properties. We show that, according to a widely implemented model for DNA denaturation, one can engineer DNA 'heattronic' devices that have a rapidly increasing thermal conductance over a narrow temperature range across the denaturation transition (~350 K). The origin of this rapid increase of conductance, or 'switching', is the softening of the lattice and suppression of nonlinear effects as the temperature crosses the transition temperature and DNA denatures. Most importantly, we demonstrate that DNA nano-junctions have a broad range of thermal tunability by varying the sequence and length, and exploiting the underlying nonlinear behavior. We discuss the role of disorder in the base sequence, as well as the relation to genomic DNA. These results set the basis for developing thermal devices out of materials with nonlinear structural dynamics, as well as understanding the underlying mechanisms of DNA denaturation. [ABSTRACT FROM AUTHOR]

Er3+-doped and Yb3+/Er3+ co-doped Gd3Sc2Ga3O12 (abbreviated as Er:GSGG and Yb,Er:GSGG, respectively) laser crystals are investigated by using a combination of spectroscopic measurements and thermal characterizations. An absorption peak of Yb,Er:GSGG crystal shifts to 970nm and its absorption band broadens obviously, which makes the crystal suitable for pumping by a 970nm laser diode (LD). This crystal also exhibits a shorter lifetime of a lower laser level, a larger emission cross section and higher thermal conductivity than those of Er:GSGG. All these factors suggest that Yb3+/Er3+ co-doping has a positive effect on improving the spectroscopic and thermal performances in GSGG based laser crystals, and imply that double-doped Yb,Er:GSGG crystal is a potential candidate as an excellent LD pumped 2.79 µm laser material. [ABSTRACT FROM AUTHOR]

We prepared a series of new binary protic ionic liquids (PILs) based on 2-imidazolidone and trifluoroacetic acid and determined their properties such as their viscosity, thermal and electrochemical properties. The results show that these PILs possess a wide liquid state temperature range, relatively good thermal stability, low viscosity and high ionic conductivity. The conductivity of the ionic liquid at a molar ratio of 3:7 was found to be 0.30 S/m and its viscosity was only 7.7 cP at room temperature. With an increase in temperature most of the samples gave better performance. The viscosity and the conductivity of the sample with a molar ratio of 5:5 was 6.1 cP and 0.32 S/m at 60°C, respectively. Infrared spectroscopy showed that the organic molecules coordinate with the H+ cation and CF3COO- anion through their polar groups (C=O and NH groups). These properties, therefore, result in these PILs being of interest for application in organic synthesis, especially as catalysts in acid catalytic reactions. [ABSTRACT FROM AUTHOR]

Temperature-dependent dc characteristics of lnGaP/GaAs heterojunction bipolar transistors (HBTs) without any surface passivation, with sulfur passivation, and with emitter ledge structure were systematically studied and demonstrated. Experimentally, due to the effective suppression of the thermal leakage current and hot-carrier injection around the emitter mesa edge, the device with ledge structure revealed lower base-surface recombination current density as well as better thermal stability and electrical reliability than the devices with/without sulfur passivation. [ABSTRACT FROM AUTHOR]

We investigated the dielectric characteristics of Hf-silicate films which were grown on Si(100) substrates by atomic layer deposition. The X-ray photoelectron spectroscopy results indicated that the atomic concentrations of HfO2 and SiO2 in the Hf-silicate films were similar to the cycle ratio between the number of HfO2 deposition cycles and that of SiO2 deposition cycles. The flatband voltage of Hf-silicate films increased as the compositional deviation from the stoichiometric compound HfSiO4 increased. For Hf-rich silicate films, the flatband voltages were lowered due to the increase of the positive fixed charge in SiO2 with the increase of SiO2 content. In addition, the crystallization temperatures were below 900°C after postannealing for 1 min in N2 ambient and accompanied the phase-separation process as the Si content increased. However, in the case of Si-rich Hf-silicate films, the increase of the effective metal work function dominated and increased the flatband voltages as the Si composition increased. The crystallization and phase separation of Hf-silicate films were not observed even after annealing at 900°C. [ABSTRACT FROM AUTHOR]

Simultaneous measurements of the thermal conductivity, thermal diffusivity and heat capacity per unit volume of monocrystalline silver bromide (AgBr), using the Gustafsson probe, in the temperature range 77-350?K are reported. Both thermal conductivity and thermal diffusivity follow Eucken's law in the temperature region studied. The heat capacity at constant pressure (CP), determined from the volumetric heat capacity, agrees with the calculated value at room temperature. The ratio of the thermal conductivity (?) of AgBr and AgCl calculated from the Leibfried-Schlömann formula is in excellent agreement with the ratio ?(AgBr)/?(AgCl)measured experimentally. The dielectric constant and loss factor of crystalline AgBr are also reported as a function of frequency in the range 100?Hz-1?MHz at room temperature. [ABSTRACT FROM AUTHOR]

The structure, magnetic and thermal properties of (FePt0.78–C0.22)–BN granular films with various BN volume concentrations are systematically studied. Compared to the FePt–C film without BN doping, the grain size distribution of the FePt grains is reduced by 50% with BN component is 10 vol.%, and the coercivity and the intrinsic switching field distributions of the film are increased 3 times and narrowed by 35%, respectively, when BN component is 6 vol.%. The improvement in magnetic properties is attributed to the enhanced chemical ordering of the FePt L10 phase. Based on the 3ω method, it is found that the relative cross-plane thermal conductivity of the FePt–C–BN layer is more correlated to the grain size distribution of the film, which decreases to the minimum value at 10 vol.% BN. Our results indicate that a certain amount of BN doping can improve the comprehensive performance of the FePt–C–BN granular films, making it a promising candidate for heat assisted magnetic recording. [ABSTRACT FROM AUTHOR]

Reverse nonequilibrium molecular dynamics (RNEMD) is employed to study the phononic thermal transport properties of C3N nanotubes. We study the effect of nanotube length and diameter on the thermal conductivity and investigate the phonon transport transition from ballistic to diffusive regime in C3N nanotubes. It is found that the thermal conductivity of C3N nanotubes is significantly lower than those of carbon nanotubes across the entire ballistic-diffusive range. In addition, significantly lower ballistic to diffusive transition length (72–80 nm) is observed in C3N nanotubes compared to carbon nanotubes. The inspection of phonon dispersion curves shows that carbon nanotubes have stiffer acoustic modes than C3N nanotubes which results in lower group velocities for C3N nanotubes. Due to the presence of nitrogen atoms, the phonon mean free paths and relaxation times of C3N nanotubes are shorter than those of the carbon nanotubes. The combined effect of lower group velocities and relaxation times leads to the lower thermal conductivity of C3N nanotubes. [ABSTRACT FROM AUTHOR]

Understanding the electrical and thermal transport properties of polycrystalline metallic nanostructures is of great interest for applications in microelectronics. In view of the diverse experimental results in polycrystalline metallic nanowires and nanofilms, it is a long-standing question whether their electrical and thermal properties can be well predicted by a practical model. By eliminating the effects of electrical and thermal contact resistances, we measure the electrical and thermal conductivities of three different polycrystalline Pt nanowires. The electron scattering at the surface is found to be diffusive, and the charge reflection coefficient at grain boundaries is proved to be a function of the melting point. The Lorenz number is observed to be suppressed from the free-electron value by about 30%, which can be explained by introducing a thermal reflection coefficient in calculating the thermal conductivity to account for the small angle scattering effect involving phonons at the grain boundaries. Using this model, both the electrical and thermal conductivities of the polycrystalline Pt nanowires are calculated at different diameters and temperatures. [ABSTRACT FROM AUTHOR]

This paper presents a study of the thermal transport properties of extra-light MgB2/Ti/Al + Al2O3 composite wires. The longitudinal thermal conductivity has been investigated as a function of temperature and magnetic field on wires differing only by an outer Al + Al2O3 sheath. The correlation between the thermal transport properties, the microstructure of the Al + Al2O3 sheath and the Al/Ti interface reactions provide important information for these thermally stabilized extra-light superconductors. The thermal runaways observed by the current–voltage characteristics of MgB2/Ti/Al + Al2O3 wires correlate well with the conductor’s temperature affected by the thermal conductivity and the resistance of the outer sheath. [ABSTRACT FROM AUTHOR]

A SrRuO3 thin film has been widely used as a metal electrode in electronic devices based on transition metal oxides, and hence it is important to understand its thermal transport properties to minimize a thermal degradation problem during the device operation. Using the time-domain thermoreflectance measurement technique, we investigate the cross-plane thermal conductivity of the SrRuO3 thin films with a thickness variation from 1 μm to 8 nm. We find that the thermal conductivity is reduced from about 6 W m−1 K−1 for the 1 μm thick film to about 1.2 W m−1 K−1 for the 8 nm thick film, and attribute this behavior to the boundary scattering of thermal carriers which originally have the mean free path of about 20 nm in a bulk state. Also, we observe a clear dip behavior of the thermal conductivity in the intermediate thickness around 30 nm which suggests an existence of a strong scattering source other than the film boundary. We explain this result by considering an additional interfacial scattering at the tetragonal-orthorhombic phase boundary which is formed during the strain relaxation with an increase of the film thickness. [ABSTRACT FROM AUTHOR]

Thermal interface materials with high thermal conductivity are essential to transfer the redundant heat and improve the reliability of integrated circuits. Here we reported high thermal conductivity in polydimethylsiloxane (PDMS) nanocomposite incorporated with few-layer graphene, which was exfoliated in chloroform with assistance of hyperbranched polyethylene-g-polyhedral oligomeric silsesquioxane copolymer (HBPE@POSS) as the stabilizer. In order to improve the compatibility and enhance the thermal property, the HBPE@POSS copolymer was synthesized via the unique chain walking polymerization mechanism, which subsequently was applied to exfoliate natural graphite into few-layer graphene in low-boiling-point solvents. The majority of resultant nanosheets with low defects was verified with lateral dimension of ~400 nm and the thickness of ~1.6 nm, which is attributed to the presence of CH-π noncovalent interaction between graphene and HBPE@POSS copolymer. The graphene nanoplates (GNPs)/polydimethylsiloxane (PDMS) nanocomposites were prepared by solution casting, in which graphene nanofillers were dispersed uniformly in the matrix due to good compatibility between PDMS and oligomeric silsesquioxane segments adsorbed on the nanosheets. The thermal conductivity of 4.0 wt% GNPs/PDMS nanocomposite reaches 0.93 W m−1 K−1, which is 400% higher than that of pure PDMS. The PDMS nanocomposite incorporated with few-layer graphene exhibits a promising prospect in thermal interface for thermal management of electronic devices, and sheds a light on the interfacial improvement mechanism of thermal conductivity for polymer composite. [ABSTRACT FROM AUTHOR]

Surface charges can modify the elastic modulus of nanostructure, leading to the change of the phonon and thermal properties in semiconductor nanostructure. In this work, the influence of surface charges on the phonon properties and phonon thermal conductivity of GaN nanofilm are quantitatively investigated. In the framework of continuum mechanics, the modified elastic modulus can be derived for the nanofilm with surface charges. The elastic model is presented to analyze the phonon properties such as the phonon dispersion relation, phonon group velocity, density of states of phonons in nanofilm with the surface charges. The phonon thermal conductivity of nanofilm can be obtained by considering surface charges. The simulation results demonstrate that surface charges can significantly change the phonon properties and thermal conductivity in a GaN nanofilm. Positive surface charges reduce the phonon energy and phonon group velocity but increase the density of states of phonons. The surface charges can change the size and temperature dependence of phonon thermal conductivity of GaN nanofilm. Based on these theoretical results, one can adjust the phonon properties and temperature/size dependent thermal conductivity in GaN nanofilm by changing the surface charges. [ABSTRACT FROM AUTHOR]

Metal chalcogenide materials, including indium selenide (InSe), have attracted attention as potential thermoelectric materials due to their intrinsically low thermal conductivity, which is due to their layered structure with weak atomic bonding. However, their low electrical conductivity should be increased for application as thermoelectric materials. In this study, we examined the electrical and thermal transport properties of 7% S- or Te-doped InSe polycrystalline alloys (InSe0.93S0.07 and InSe0.93Te0.07). These anion substitutions increased the electrical conductivity of InSe, while the enhancement was larger for the Te-doped InSe with a smaller bandgap. The negative Seebeck coefficient did not change significantly upon doping, resulting in enhancement of the power factor. Doping caused a relatively large reduction of thermal conductivity due to additional point defect phonon scattering. Consequently, the thermoelectric figure of merit (zT) increased by 62% and 230% to a maximum of 0.13 and 0.28 at 735 K for InSe0.93S0.07 and InSe0.93Te0.07, respectively, which offers the possibility of InSe-based thermoelectric materials. Cation doping could increase the zT of S/Te-doped InSe further. [ABSTRACT FROM AUTHOR]

One-dimensional nanotubes, such as carbon nanotube (CNT) and C3N nanotube (C3NNT), are attracting growing research interest due to their excellent electrical and thermal properties. In this work, the thermal transport of a single-walled C3NNT is investigated in comparison with a single-walled CNT using classical molecular dynamic simulations. We firstly observe that the thermal conductivity (k) of C3NNT is lower than that of CNT. Due to the phonon scattering in the N atoms of C3NNT, the energy is localized around the N atoms. Monotonic decreasing trends of k with increasing temperature are shown in CNT and C3NNT, indicating strong Umklapp phonon scattering. Afterwards, uniaxial strains from −10% to 14% are applied to the nanotubes, and the thermal conductivity initially increases and then decreases. Phonon density of states, phonon dispersions, participation ratios, and spatial distribution of energy are used to analyze the phonon behaviors in nanotubes. This work provides fundamental thermo-physical knowledge to the thermal management of CNT and C3NNT based nanoelectronics. [ABSTRACT FROM AUTHOR]