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1.
    
Phase change materials (PCMs) are a class of thermo-responsive materials that can be utilized to trigger a phase transition which gives them thermal energy storage capacity. Any material with a high heat of fusion is referred to as a PCM that is able to provide cutting-edge thermal storage. PCMs are commercially used in many applications like textile industry, coating, and cold storage typically for heat control. These intriguing substances have recently been rediscovered and employed in a broad range of life science applications, including biological, human body, biomedical, pharmaceutical, food, and agricultural applications. Benefiting from the changes in physicochemical properties during the phase transition makes PCMs also functional for barcoding, detection, and storage. Paraffin wax and polyethylene glycol are the most commonly studied PCMs due to their low toxicity, biocompatibility, high thermal stability, high latent enthalpy, relatively wide transition temperature range, and ease of chemical modification. Current challenges in employing PCMs for life science applications include biosafety and/or engineering difficulties. The focus of this review article is on the life science applications, evaluation, and safety aspects of PCMs. Herein, the advances and the potential of employing PCMs as a versatile platform for various types of life science applications are highlighted.  相似文献   

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The development of solar energy conversion materials is critical to the growth of a sustainable energy infrastructure in the coming years. A novel hybrid material based on single‐walled carbon nanotubes (SWNTs) and form‐stable polymer phase change materials (PCMs) is reported. The obtained materials have UV‐vis sunlight harvesting, light‐thermal conversion, thermal energy storage, and form‐stable effects. Judicious application of this efficient photothermal conversion to SWNTs has opened up a rich field of energy materials based on novel SWNT/PCM composits with enhanced performance in energy conversion and storage.  相似文献   

4.
刘岩  朱辰  张利明  高平 《激光与红外》2019,49(12):1425-1430
通常,高功率光纤激光器采用如水冷、风冷等传统散热方式,往往无法满足实际需求(水冷体积重量大,风冷散热不足),进而导致激光器不能满足一些特殊应用。文章利用相变储能的特性,采用相变制冷方法,对全光纤激光器热处理进行了理论分析与实验研究,实现了工作波长1080 nm,最大输出功率409 W的连续光纤激光输出,光-光转换效率80 %,有效减小了体积、重量,为高功率光纤激光器的热管理提供了新方法。  相似文献   

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The design of sustainable self-healing phase change materials (SHPCMs) remains challenging depending on sustainable fatty alcohols without compromising high enthalpy efficiency. Herein, the semi-interpenetrating network (semi-IPN)-based SHPCMs are developed by introducing dynamic disulfide crosslinking polyurethane networks and sustainable fatty alcohols as phase change components in a semi-IPN structure, enabling the combination of ultrahigh enthalpy efficiency of ≈100% and excellent self-healing ability with 99% of mechanical stain healing efficiency. The latent heat (61.6–144.3 J g−1) and phase change temperature (29.2–64.2 °C) can be readily adjusted by the type and content of fatty alcohols in SHPCMs. The SHPCMs present high thermal reliability, thermal and shape stability, and solid-like rheological properties benefiting from the advantage of the semi-IPN structure. The SHPCMs are endowed with tunable mechanical stress (1.23–6.16 MPa) and strain (5.77–379.48%). More importantly, the SHPCMs can be nearly completely self-healed after thermal stimulus, complying with the Arrhenius model, with a low activation energy of 33.831 kJ mol−1. This innovative strategy opens new avenues for preparing efficient and durable thermal energy storage materials with high enthalpy efficiency, self-healing ability, and sustainable phase change components, broadening their potential applications.  相似文献   

6.
    
To alleviate resource shortage and environmental pollution, solar energy can be converted into thermal energy stored in phase change materials and in turn generate electrical energy. To enhance the solar energy utilization efficiency of solar-thermal-electrical conversion devices and prevent the heat loss to the environment at night, an intelligent solar-responsive phase-change system is innovatively designed consisting of a graphene aerogel film/paraffin wax stamen with an ultra-high thermal conductivity of 46.7 W m−1 K−1, and thermally preserving aerogel film/liquid crystal elastomer bilayer petals that can bend solar-responsively by the synergistic effect of solar-thermal energy conversion and heat-induced contraction. The solar-responsive phase-change system achieves daytime blooming for solar-thermal conversion with simultaneous energy storage and nighttime closing for minimizing heat loss to the environment, exhibiting a high solar-thermal conversion and energy storage efficiency of 89.4% and delaying its temperature drop by the thermal preservation effect of the petals. The assembled solar-responsive solar-thermal-electric generator can reach an output voltage of 1033.8 mV at a light intensity of 500 mW cm−2 and continue to generate electrical energy during nighttime, holding tremendous promise in efficient solar energy conversion, storage, and utilization.  相似文献   

7.
设计了一种中、高温熔点金属材料固-液相变点温度附近热物性动态测算方法,并与计算机实时数据采集和测控技术结合起来,研制了相应的动态测试仪。通过实验测定相界面的移动速率与相变导热反问题的数值计算相结合的办法来确定被测材料的热物性。分别对相变室、炉体、相界面探测器、温度在线检测与控制系统、测试过程进行了设计,对测试系统的测量误差进行了定量分析,发现采用此方法测试的系统误差不超过3%。用已知热物性的锌、铝金属对此方法进行了检定,得到了较为满意的测试结果。  相似文献   

8.
设计了一种中、高温熔点金属材料固-液相变点温度附近热物性动态测算方法,并与计算机实时数据采集和测控技术结合起来,研制了相应的动态测试仪。通过实验测定相界面的移动速率与相变导热反问题的数值计算相结合的办法来确定被测材料的热物性。分别对相变室、炉体、相界面探测器、温度在线检测与控制系统、测试过程进行了设计,对测试系统的测量误差进行了定量分析,发现采用此方法测试的系统误差不超过3%。用已知热物性的锌、铝金属对此方法进行了检定,得到了较为满意的测试结果。  相似文献   

9.
    
Over the past decade, wood‐derived materials have attracted enormous interest for both fundamental research and practical applications in various functional devices. In addition to being renewable, environmentally benign, naturally abundant, and biodegradable, wood‐derived materials have several unique advantages, including hierarchically porous structures, excellent mechanical flexibility and integrity, and tunable multifunctionality, making them ideally suited for efficient energy storage and conversion. In this article, the latest advances in the development of wood‐derived materials are discussed for electrochemical energy storage systems and devices (e.g., supercapacitors and rechargeable batteries), highlighting their micro/nanostructures, strategies for tailoring the structures and morphologies, as well as their impact on electrochemical performance (energy and power density and long‐term durability). Furthermore, the scientific and technical challenges, together with new directions of future research in this exciting field, are also outlined for electrochemical energy storage applications.  相似文献   

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Electro‐thermal phase‐change materials (PCMs) enable continuous operation of heating‐related processes, which is urgently required for modern thermal‐management devices. Driven by the unmet needs to develop promising electro‐thermal PCMs with low operation voltage and high electro‐thermal storage efficiency simultaneously, unique ZIF@MOF‐derived carbon‐nanotube (CNT)‐penetrated porous carbon supports for electro‐thermal PCMs are introduced. The network structure of the support decreases the resistivity of the composite and ensures a low operation voltage. Furthermore, abundant CNT cores in porous carbon shells facilitate interfacial interaction between the PCMs and the support and realize a rapid heat transformation. It is noted that low thermal conductive porous carbon shells prevent convective heat dissipation at the CNT‐air interface to a great degree which leads to enhanced electro‐thermal storage efficiency. Consequently, the obtained electro‐thermal PCMs exhibit a low operation voltage of 1.1 V and a record‐high electro‐thermal storage efficiency of 94.5%, which shows great potential in thermal management of electronic devices.  相似文献   

11.
    
The use of phase‐change materials for a range of exciting new optoelectronic applications from artificial retinas to ultrahigh‐resolution displays requires a thorough understanding of how these materials perform under a combination of optical and electrical stimuli. This study reports for the first time the complex link between the electronic and optical properties in real‐world crossbar nanoscale devices constructed by confining a thin layer of Ge2Sb2Te5 between transparent indium tin oxide electrodes, forming an optical nanocavity. A novel proof‐of‐concept device that can be operated by a combination of optical and electrical stimuli is presented, leading the way for the development of further applications based on mixed‐mode electro‐optical operation.  相似文献   

12.
To remedy the drawbacks of weak solar-thermal conversion capability, low thermal conductivity, and poor structural stability of phase change materials, pyramidal graphitized chitosan/graphene aerogels (G-CGAs) with numerous radially oriented layers are constructed, in which the long-range radial alignment of graphene sheets is achieved by a novel directional-freezing strategy. A G-CGA/polyethylene glycol phase change composite exhibits a thermal conductivity of 2.90 W m−1 K−1 with a latent heat of 178.8 J g−1, and achieves a superior solar-thermal energy conversion and storage efficiency of 90.4% and an attractive maximum temperature of 99.7 °C under a light intensity of 200 mW cm−2. Inspired by waterlilies, solar-responsive phase change composites (SPCCs) are designed for the first time by assembling the G-CGA/polyethylene glycol phase change composites with solar-driven bilayer films, which bloom by day and close by night. The heat preservation effect of the solar-driven films leads to a higher temperature of SPCC for a longer period at night. The SPCC-based solar–thermal–electric generator achieves output voltages of 499.2 and 1034.9 mV under light intensities of 200 and 500 mW cm−2, respectively. Even after stopping the solar irradiation, the voltage output still occurs because of the latent heat release and the heat preservation of the films.  相似文献   

13.
    
Ge2Sb2Te5 (GST) has demonstrated its outstanding importance among rapid phase‐change (PC) materials, being applied for optical and electrical data storage for over three decades. The mechanism of nanosecond phase change in GST, which is vital for its application, has long been disputed: various, quite diverse scenarios have been proposed on the basis of various experimental and theoretical approaches. Nevertheless, one central question still remains unanswered: why is amorphous GST stable at room temperature for long time while it can rapidly transform to the crystalline phase at high temperature? Here it is revealed for the first time, by modelling the amorphous structure based on synchrotron radiation anomalous X‐ray scattering data, that germanium and tellurium atoms form a “core” Ge‐Te network with ring formation. It is also suggested that the Ge‐Te network can stabilize the amorphous phase at room temperature and can persist in the crystalline phase. On the other hand, antimony does not contribute to ring formation but constitutes a “pseudo” network with tellurium, in which the characteristic Sb–Te distance is somewhat longer than the covalent Sb–Te bond distance. This suggests that the Sb‐Te pseudo network may act as a precursor to forming critical nuclei during the crystallization process. The findings conclude that the Ge‐Te core network is responsible for the outstanding stability and rapid phase change of the amorphous phase while the Sb‐Te pseudo network is responsible for triggering critical nucleation.  相似文献   

14.
    
Dependence of transformation temperatures of ternary and quaternary NiTi‐based shape memory alloys on the number (ev/a) and concentration (cv) of valence electrons is investigated. Two distinct trends of transformation temperatures with respect to the number of valence electrons per atom are found depending on whether ev/a = 7 or ev/a ≠ 7. Clear correlations between transformation temperatures and cv exist. Ms and As decrease consistently from 900 to ?100 °C, and 950 to ?30 °C, respectively, with increasing cv from 0.145 to 0.296. The relationship of electron concentration on the elastic moduli of the NiTi‐based alloys is discussed. The possible influence of the atomic size of alloying elements on transformation hysteresis is introduced.  相似文献   

15.
    
The dielectric pulse effect is of interest for many applications such as sensors, smart triggers, and energy storage. In this paper, a general approach to achieve a room temperature dielectric pulse effect via solid–liquid phase transition in organic mixtures formed by conductive surfactants and insulating fluid is introduced. The dielectric pulse is caused by the self‐formed blocking layer appearing during the solid–liquid phase transition by mixing Span80 and hexadecane. Using 50 Vol% Span80/hexadecane mixture, the dielectric peak intensity of 1191.6 is achieved at 11.9 °C. The dielectric peak intensity and the trigger temperature of mixtures can be tuned by changing the proportions of the components, the temperature ramping rate, and the components. The generality of the approach is also demonstrated in other organic matter such as Span series, alcohols, alkanes and their mixtures.  相似文献   

16.
    
Phase change memory (PCM) is one of the leading candidates for neuromorphic hardware and has recently matured as a storage class memory. Yet, energy and power consumption remain key challenges for this technology because part of the PCM device must be self-heated to its melting temperature during reset. Here, it is shown that this reset energy can be reduced by nearly two orders of magnitude by minimizing the pulse width. A high-speed measurement setup is utilized to probe the energy consumption in PCM cells with varying pulse width (0.3–40 nanoseconds) and uncover the power dissipation dynamics. A key finding is that the switching power (P) remains unchanged for pulses wider than a short thermal time constant of the PCM (τth < 1 ns in 50 nm diameter device), resulting in a decrease of energy (E = P × τ) as the pulse width τ is reduced in that range. Thermal confinement during short pulses is achieved by limiting the heat diffusion time. The improved programming scheme reduces reset energy density below 0.1 nJ µm−2, over an order of magnitude lower than state-of-the-art PCM, potentially changing the roadmap of future data storage technology and paving the way toward energy-efficient neuromorphic hardware.  相似文献   

17.
相变材料及其在热红外伪装领域的应用研究   总被引:1,自引:0,他引:1       下载免费PDF全文
综述了各种相变材料(PCM)的性能特点及研究现状,研究分析了相变材料在军事热红外伪装领域中的应用机理及其在伪装纺织品和假目标中的应用,最后探讨了将相变材料应用于热红外伪装需要解决的问题.  相似文献   

18.
    
Historically, the application of phase‐change materials and devices has been limited to the provision of non‐volatile memories. Recently, however, the potential has been demonstrated for using phase‐change devices as the basis for new forms of brain‐like computing, by exploiting their multilevel resistance capability to provide electronic mimics of biological synapses. Here, a different and previously under‐explored property that is also intrinsic to phase‐change materials and devices, namely accumulation, is exploited to demonstrate that nanometer‐scale electronic phase‐change devices can also provide a powerful form of arithmetic computing. Complicated arithmetic operations are carried out, including parallel factorization and fractional division, using simple nanoscale phase‐change cells that process and store data simultaneously and at the same physical location, promising a most efficient and effective means for implementing beyond von‐Neumann computing. This same accumulation property can be used to provide a particularly simple form phase‐change integrate‐and‐fire “neuron”, which, by combining both phase‐change synapse and neuron electronic mimics, potentially opens up a route to the realization of all‐phase‐change neuromorphic processing.  相似文献   

19.
    
Metasurfaces, planer artificial materials composed of subwavelength unit cells, have shown superior abilities to manipulate the wavefronts of electromagnetic waves. In the last few years, metasurfaces have been a burgeoning field of research, with a large variety of functional devices, including planar lenses, beam deflectors, polarization converters, and metaholograms, being demonstrated. Up to date, the majority of metasurfaces cannot be tuned postfabrication. Yet, the dynamic control of optical properties of metasurfaces is highly desirable for a plethora of applications including free space optical communications, holographic displays, and depth sensing. Recently, much effort has been made to exploit active materials, whose optical properties can be controlled under external stimuli, for the dynamic control of metasurfaces. The tunability enabled by active materials can be attributed to various mechanisms, including but not limited to thermo‐optic effects, free‐carrier effects, and phase transitions. This short review summarizes the recent progress on tunable metasurfaces based on various approaches and analyzes their respective advantages and challenges to be confronted with. A number of potential future directions are also discussed at the end.  相似文献   

20.
    
The increasing development of wearable, portable, implantable, and highly integrated electronic devices has led to an increasing demand for miniaturization of energy storage devices. In recent years, supercapacitors, as an energy storage device, have received enormous attention owing to their excellent properties of quick charge and discharge, high power density, and long life cycle with minimal maintenance. Micro‐supercapacitors (MSCs) as a promising candidate for miniaturized energy storage components have undergone considerable theoretical and experimental investigations. Particularly, planar MSCs with a 2D architecture design have more attractive application prospects due to their flexible design and excellent electrochemical performance. However, the major drawbacks of MSCs are their intrinsically low energy density. For this reason, researchers have conducted much investigation to improve their energy density in order to promote their practical application. Herein, the recent development and progress of planar MSCs from the scope of the substrates, electrode materials, fabrication methods, electrochemical properties, and applications are discussed. Finally, the currently existing challenges and developments associated with planar MSCs are also discussed. All in all, planar MSCs have great application potential in various fields of electrochemical energy storage, self‐powered wireless sensors, and stimuli‐responsive and photoresponsive, alternating current line filtering.  相似文献   

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