Controllable Thermal Rectification Realized in Binary Phase Change Composites

Chen, Renjie; Cui, Ya-Long; Tian, He; Yao, Ruimin; Liu, Zhenpu; Shu, Yi; Li, Cheng; Yang, Yi; Ren, Tian‐Ling; Zhang, Gang; Zou, Ruqiang

doi:10.1038/srep08884

Cited by 57 publications

(31 citation statements)

References 38 publications

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“…Since the first observation of thermal rectification by Starr in 1936, thermal rectification has been realized through various mechanisms: asymmetric nanostructured geometry, evaporation/condensation, infrared emission, temperature dependence of thermal conductivity, mechanical tensile strain and an imperfect interface junction, as well as nonlinear lattice models, as reviewed in the literature . Based on the mechanism of the temperature dependence of thermal conductivity, a thermal diode can be realized by coupling two materials with different temperature dependences of thermal conductivities.…”

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

“…NTC thermal‐switching materials are widely studied in phase change thermal diodes, such as paraffin (eicosane, octadecane, hexadecane, etc. ), PEG, and crystalline polyethylene (PE) fiber . The choice of the temperature boundary of rectification is abundant due to the broad range of phase change temperatures of the aforementioned PCM.…”

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

“…The confinement by a porous supporting scaffold of solid–liquid PCM is necessary for the fabrication of phase change thermal diodes. Our group designed a form‐stable thermal rectifier by encapsulating two kinds of PCMs into both ends of an reduced GO (rGO) aerogel skeleton . Eicosane and PEG4000 were chosen to form the binary junction due to their different thermal conductivity thermoresponsive ( Figure b), different melting points and immiscibility in a liquid state.…”

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

“…c) The temperature‐dependent thermal rectification turned on by the phase change process. a–c) Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/) . Copyright 2015, Springer Nature.…”

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

See 3 more Smart Citations

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

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292

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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Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

Section: Applications Of Pcms With Tuned Thermal Conductivitymentioning

confidence: 99%

See 2 more Smart Citations

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

Self Cite

292

136

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“…Alternative mechanisms include geometrical limitations, utilizing changes in boundary scattering to direct thermal transport and establish a gradient in the thermal conductivity. Since the relevant size scales need to be small enough to exhibit size effects, this is often seen in patterned graphene and graphene oxide that is shaped to have variable size effect based phonon scattering [151,152]. As will be discussed in Ch.…”

mentioning

confidence: 99%

Understanding Phonon Interactions with Defects in Functional Oxide Materials

Donovan¹

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Understanding of nano-scale thermal transport has enabled significant advances in a wide variety of fields including microelectronics, alternative energy, optics, and many more [1][2][3][4]. Utilized in many of these applications are a class of materials known as functional oxides. These materials are oxygen compounds with specific functional properties of interest (e.g., dielectrics [5][6][7][8], piezoelectrics [9][10][11], photovoltaics [12][13][14], thermoelectrics [15][16][17][18][19]). Often it is the defects in these materials that enable functionality and, depending on the processing and operating conditions, the concentration and types of defects that are present in these materials can vary widely [20]. In this dissertation, I aim to identify the role that defects play in functional oxide materials with respect to thermal transport.The major thermal carriers in most functional oxide crystals are collective lattice vibrations, or phonons [21]. Phonon-dominated thermal conductivity is dictated by the scattering of these thermal carriers with a variety of other components or the material system, including defects in the crystal [22,23]. I concentrate on three types of defects that are common in functional oxides: boundaries, extrinsic point defects, and intrinsic point defects.Boundaries such as film boundaries and grain boundaries with nano-scale dimensions can be detrimental to the thermal conductivity of a material. As the length of the uninterrupted crystal reduces to the phonon mean free paths in the crystal, phonons will scatter readily off of nano-scale boundaries and will not be able to propagate as they would in a bulk environment. This becomes particularly relevant in technologies such as the microelectronics industry, where device size scales are well below common phonon mean free paths in the constituent materials. To study this, I turn to one of the more common functional oxides used in the microelectronics industry, BaTiO 3 .I study the effects of nano-scale grains on thin films of BaTiO 3 grown via chemical solution deposition. The films studied are 150 nm and range in grain size from 36 nm -63 nm. I show that the thermal conductivity of these nano-grained films scales with the grain size and film thickness and demonstrate agreement of this trend with analytical models. This result demonstrates that despite a complex crystal structure, there is a mean free path spectrum of phonons in BaTiO 3 that significantly exceeds the dimensions of the grains and film (contrary to the common "gray" mean 2 free path assumption seen in literature).To address the role of extrinsic point defects, or dopants, on the thermal conductivity of functional oxides, I study the effects of dysprosium doping in thin films of cadmium oxide deposited by molecular beam epitaxy. In this experiment, the addition of Dy dopants in CdO actually increases the thermal conductivity initially, owing to a reduction in the equilibrium concentration of oxygen vacancies (a type of defect that is intrinsic to all oxides). The de...

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Thermal Conductivity of Amorphous Materials

Zhou

Cheng

Chen

et al. 2019

Adv Funct Materials

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194

110

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Thermal conductivity is one of the most fundamental properties of solid materials. The thermal conductivity of ideal crystal materials has been widely studied over the past hundreds years. On the contrary, for amorphous materials that have valuable applications in flexible electronics, wearable electrics, artificial intelligence chips, thermal protection, advanced detectors, thermoelectrics, and other fields, their thermal properties are relatively rarely reported. Moreover, recent research indicates that the thermal conductivity of amorphous materials is quite different from that of ideal crystal materials. In this article, the authors systematically review the fundamental physical aspects of thermal conductivity in amorphous materials. They discuss the method to distinguish the different heat carriers (propagons, diffusons, and locons) and the relative contribution from them to thermal conductivity. In addition, various influencing factors, such as size, temperature, and interfaces, are addressed, and a series of interesting anomalies are presented. Finally, the authors discuss a number of open problems on thermal conductivity of amorphous materials and a brief summary is provided.

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Controllable Thermal Rectification Realized in Binary Phase Change Composites

Cited by 57 publications

References 38 publications

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

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

Understanding Phonon Interactions with Defects in Functional Oxide Materials

Thermal Conductivity of Amorphous Materials

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