Analysis of Thermal Diodes Enabled by Junctions of Phase Change Materials

Cottrill, Anton L.; Strano, Michael S.

doi:10.1002/aenm.201500921

Cited by 47 publications

(52 citation statements)

References 32 publications

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“…al. 21 analyzed the thermal rectification in a single phase change material. However, they limited their analysis to the simplest case with only one phase change material and thus can only provide rectification defined by the contrast of the high and low thermal conductivity phase of that individual material.…”

Section: Introductionmentioning

confidence: 99%

Thermal Rectification via Heterojunctions of Solid-State Phase-Change Materials

2018

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Nonlinear thermal transport can arise naturally in materials with strongly temperature-dependent thermal conductivities, however, this is exceedingly rare and weak. If a general strategy could be devised to yield nonlinear thermal transport, it would provide an avenue to controlling heat flow and realizing nonlinear thermal devices. Phase change materials, which can exist in two states with distinct thermal conductivities, provide a unique opportunity to realize nonlinear thermal transport. In this work, we develop an analytical framework upon which we propose a material architecture for actualizing one type of nonlinear thermal transport, thermal rectification, where heat flux is biased in one direction. Our findings show that a heterojunction of two tunable phase change materials can demonstrate strong thermal rectification. The magnitude of thermal rectification is analyzed as a function of the phase change properties of each material, and we determine the fundamental heat flux relations for each direction in these heterojunctions and criteria to separate the various phase situations which can occur. Finally, the analytical framework is applied to a junction comprised of two phase change materials, polyethylene and vanadium dioxide, and demonstrate a maximal theoretical rectification factor of ~140%. This analysis provides an important analytical tool in helping researchers design thermal circuits or advanced thermal energy storage media.

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Section: Introductionmentioning

confidence: 99%

Thermal Rectification via Heterojunctions of Solid-State Phase-Change Materials

2018

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“…The combination of native oxide layer and alloying with germanium in concentration as small as 5% reduces the thermal conductivity of silicon membranes to 100 time lower than the bulk. In addition, the resonance mechanism produced by native oxide surface layers is particularly effective for thermal condutivity reduction even at very low temperatures, at which only low frequency modes are populated.Controlling terahertz vibrations and heat transport in nanostructures has a broad impact on several applications, such as thermal management in micro-and nano-electronics, renewable energies harvesting, sensing, biomedical imaging and information and communication technologies [1][2][3][4][5][6][7][8]. Significant efforts have been made to understand and engineer heat transport in nanoscale silicon due to its natural abundance and technological relevance [9][10][11][12].…”

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confidence: 99%

Native surface oxide turns alloyed silicon membranes into nanophononic metamaterials with ultralow thermal conductivity

et al. 2017

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A detailed understanding of the relation between microscopic structure and phonon propagation at the nanoscale is essential to design materials with desired phononic and thermal properties. Here we uncover a new mechanism of phonon interaction in surface oxidized membranes, i.e., native oxide layers interact with phonons in ultra-thin silicon membranes through local resonances. The local resonances reduce the low frequency phonon group velocities and shorten their mean free path. This effect opens up a new strategy for ultralow thermal conductivity design as it complements the scattering mechanism which scatters higher frequency modes effectively. The combination of native oxide layer and alloying with germanium in concentration as small as 5% reduces the thermal conductivity of silicon membranes to 100 time lower than the bulk. In addition, the resonance mechanism produced by native oxide surface layers is particularly effective for thermal condutivity reduction even at very low temperatures, at which only low frequency modes are populated.Controlling terahertz vibrations and heat transport in nanostructures has a broad impact on several applications, such as thermal management in micro-and nano-electronics, renewable energies harvesting, sensing, biomedical imaging and information and communication technologies [1][2][3][4][5][6][7][8]. Significant efforts have been made to understand and engineer heat transport in nanoscale silicon due to its natural abundance and technological relevance [9][10][11][12]. In the past decade researchers explored strategies to obtain silicon based materials with low thermal conductivity (TC) and unaltered electronic transport coefficients, so to achieve high thermoelectric figure of merit and enable silicon-based thermoelectric technology [11][12][13][14][15][16][17][18].From the earlier studies it was recognized that lowdimensional silicon nanostructures, such as nanowires, thin films and nano membranes feature a largely reduced TC, up to 50 times lower than that of bulk at room temperature. TC reduction becomes more prominent with the reduction of the characteristic dimension of the nanostructures [19][20][21][22]. Theory and experiments consistently show that surface disorder and the presence of disordered material at surfaces play a major role in determining the TC of nanostructures [12,[23][24][25]. However, a comprehensive understanding of the physical mechanisms underlying so large TC reduction is lacking. The effect of surface roughness and surface disorder on phonons has been so far interpreted in terms of phonon scattering [26][27][28][29][30], but scattering would not account for mean free path reduction of long-wavelength low-frequency modes. Recent theoretical work demonstrated that surface nanostructures, such as nanopillars at the surface of thin films or nanowires, can efficiently reduce TC through resonances, a mechanism that is intrinsically different from scattering [31,32]. Surface resonances alter directly phonon dispersion relations by hybridizing with prop...

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“…It is worth mentioning that the difference in the thermal conductivities between two phases of some NTC thermal switching materials can be greatly enhanced by nanoparticle additives, such as CNTs, graphite flakes, and copper nanowires, which can further improve the thermal rectification performance. In addition, for the ideal length or thickness ratio of two injunction ends, the optimum temperature biases should also be considered in the design of thermal diodes . In short, there is still a great space for the development of high‐performance thermal diodes based on PCM.…”

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

“…In addition, for the ideal length or thickness ratio of two injunction ends, the optimum temperature biases should also be considered in the design of thermal diodes. [214] In short, there is still a great space for the development of high-performance thermal diodes based on PCM.…”

Section: Thermal Diodes Based On Ntc/ptc Thermal-switching Materialsmentioning

confidence: 99%

Engineering the Thermal Conductivity of Functional Phase‐Change Materials for Heat Energy Conversion, Storage, and Utilization

Yuan

Shi

Aftab

et al. 2019

Adv Funct Materials

257

136

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Thermal energy storage technologies based on phase‐change materials (PCMs) have received tremendous attention in recent years. These materials are capable of reversibly storing large amounts of thermal energy during the isothermal phase transition and offer enormous potential in the development of state‐of‐the‐art renewable energy infrastructure. Thermal conductivity plays a vital role in regulating the thermal charging and discharging rate of PCMs and improving the heat‐utilization efficiency. The strategies for tuning the thermal conductivity of PCMs and their potential energy applications, such as thermal energy harvesting and storage, thermal management of batteries, thermal diodes, and other forms of energy utilization, are summarized systematically. Furthermore, a research perspective is given to highlight emerging research directions of engineering advanced functional PCMs for energy applications.

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Analysis of Thermal Diodes Enabled by Junctions of Phase Change Materials

Cited by 47 publications

References 32 publications

Thermal Rectification via Heterojunctions of Solid-State Phase-Change Materials

Thermal Rectification via Heterojunctions of Solid-State Phase-Change Materials

Native surface oxide turns alloyed silicon membranes into nanophononic metamaterials with ultralow thermal conductivity

Engineering the Thermal Conductivity of Functional Phase‐Change Materials for Heat Energy Conversion, Storage, and Utilization

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