Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal condu...Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal conductivities of phase-change materials(PCMs)promote Joule heating dissi-pation.Repeated phase transitions also induce long-range atomic diffusion,limiting the durability.To address these challenges,phase-change heterostructure(PCH)devices that incorporate confinement sub-layers based on transition-metal dichalcogenide materials have been developed.In this study,we engi-neered a PCH device by integrating HfTe_(2),which has low thermal conductivity and excellent stability,into the PCM to realize PCRAM with enhanced thermal efficiency and structural stability.HEAT sim-ulations were conducted to validate the superior heat confinement in the programming region of the HfTe_(2)-based PCH device.Moreover,electrical measurements of the device demonstrated its outstanding performance,which was characterized by a low RESET current(∼1.6 mA),stable two-order ON/OFF ratio,and exceptional cycling endurance(∼2×10^(7)).The structural integrity of the HfTe_(2)confinement sub-layer was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy.The material properties,including electrical conductivity,cohesive energy,and electronegativity,substantiated these findings.Collectively,these results revealed that the HfTe_(2)-based PCH device can achieve significant improvements in performance and reliability compared with conventional PCRAM devices.展开更多
Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquef...Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.展开更多
The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to effi...The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to efficiently manage energy storage and release.This technology requires lower pressure and temperature control,resulting in reduced energy consumption and improved efficiency.Additionally,it is less restricted by geographical factors to a certain extent,enabling the formation of a closed-loop system.This contributes to the development of new energy utilization systems.The article examines and compares two experimental energy storage projects employing elastic gasbags to maintain a constant pressure supply of carbon dioxide on the low-pressure side.It further details the precise calculation methods for system cycle efficiency and energy storage density while analyzing energy losses incurred during the storage and release phases.Finally,an economic analysis is conducted using specific data,demonstrating that optimizing temperature and pressure parameters at various nodes enhances overall system efficiency while reducing energy consumption.Furthermore,the study highlights the system's high sensitivity to grid electricity prices.This research is anticipated to contribute to the development of more efficient and reliable energy storage solutions for power systems,addressing the growing energy demands and sustainability challenges.展开更多
To address the limitations of conventional energy systems and optimize the energy conversion pathways and efficiency,a type of“five-in-one”multifunctional phase-change composite with magnetothermal,electrothermal,so...To address the limitations of conventional energy systems and optimize the energy conversion pathways and efficiency,a type of“five-in-one”multifunctional phase-change composite with magnetothermal,electrothermal,solar-thermal,and thermoelectric energy conversion and electromagnetic shielding functions is developed for multipurpose applications.Such a novel phase-change composite is fabricated by an innovative combination of paraffin wax(PW)as a phase-change material and a carbonized polyimide/Kevlar/graphene oxide@ZIF-67 complex aerogel as a supporting material.The carbonized complex aerogel exhibits a unique bidirectional porous structure with high porosity and robust skeleton to support the loading of PW.The reduced graphene oxide and Co NC resulting from high-temperature carbonization are anchored on the aerogel skeleton to generate high thermal conduction and magnetic effect,enhancing the phonon and electron transfer of the aerogel and improving its energy conversion efficiency.The phase-change composite not only exhibits excellent solar-thermal,thermoelectric,electrothermal,and magnetothermal energy conversion performance,but also achieves high electromagnetic interference shielding effectiveness of 66.2 d B in the X-band.The introduction of PW significantly improves the thermal energy-storage capacity during multi-energy conversion.The developed composite exhibits great application potential for efficient solar energy utilization,sustainable power generation,outdoor deicing,human thermal therapy,and electronic device protection.展开更多
In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.I...In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.In particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor line.Chip manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line process.In this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device performance.After a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide platforms.Next,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode operation.Finally,the fabrication of photonic and photonic–electronic neuromorphic computing systems is reviewed.These systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern recognition.With large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.展开更多
This article,based on authors＇ long-term study,proposes an improved foamed-Ni-packed phase-change thermal storage canister,which takes advantage of the foamed-Ni characteristic of instinctive porous structure and exc...This article,based on authors＇ long-term study,proposes an improved foamed-Ni-packed phase-change thermal storage canister,which takes advantage of the foamed-Ni characteristic of instinctive porous structure and excellent properties to ameliorate its void distribution and thermal conductivity. The improved canister and the unimproved one without foamed-Ni package,are put to heat absorbing and releasing tests to investigate the effects of heat absorbing temperature upon the phase-change materials （PCM） melting time under three temperature schemes by using platinum resistance thermometers （PT100） and data acquisition modules （ADAM-4000） to gather the data of varying temperature. Afterwards,the computerized tomography （CT） is employed to scan the void distribution in both canisters. Compared to the unimproved canister,the experimental results evidence the superiority of the improved one in higher uniformity in void and temperature distribution as well as faster thermal responses.展开更多
The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,...The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.展开更多
To investigate thermal protection effects of heat sinking vest with phase-change material （PCM）, human thermoregulation model is introduced, and a thermal mathematical model of heat transfer with phase change has be...To investigate thermal protection effects of heat sinking vest with phase-change material （PCM）, human thermoregulation model is introduced, and a thermal mathematical model of heat transfer with phase change has been developed with the enthalpy method. The uniform energy equation is constructed for the whole domain, and the equation is implicitly discreted by control volume and finite difference method. Then the enthalpy in each node is solved by using chasing method to calculate the tridiagonal equations, and the inner surface temperature of PCM could be obtained. According to the human thermoregulation model of heat sinking vest, the dynamic temperature distribution and sweat of the body are solved. Calculation results indicate that the change of core temperature matches the experimental result, and the sweat difference is small. This thermal mathematical model of heat transfer with phase change is credible and appropriate. Through comparing the dynamic temperature distribution and sweat of the body wearing heat sinking vest to results of the body not wearing this clothing, it is evident that wearing heat sinking vest can reduce the body heat load significantly.展开更多
Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving h...Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures,which is critical for the efficient processing and reliable storage of data at full capacity.Herein,we report a novel PCM device based on Ta-doped antimony telluride(Sb2Te),which exhibits both high-speed characteristics and excellent high-temperature characteristics,with an operation speed of 2 ns,endurance of >106 cycles,and reversible switching at 140℃.The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure,which improves the thermal stability.Furthermore,the small grains in the three-dimensional limit lead to an increased energy efficiency and a reduced risk of layer segregation,reducing the power consumption and improving the long-term endurance.Our findings for this new Ta-Sb2Te material system can facilitate the development of PCMs with improved performance and novel applications.展开更多
Recent years, optically controlled phase-change memory draws intensive attention owing to some advanced applications including integrated all-optical nonvolatile memory, in-memory computing, and neuromorphic computing...Recent years, optically controlled phase-change memory draws intensive attention owing to some advanced applications including integrated all-optical nonvolatile memory, in-memory computing, and neuromorphic computing. The light-induced phase transition is the key for this technology. Traditional understanding on the role of light is the heating effect. Generally, the RESET operation of phase-change memory is believed to be a melt-quenching-amorphization process. However, some recent experimental and theoretical investigations have revealed that ultrafast laser can manipulate the structures of phase-change materials by non-thermal effects and induces unconventional phase transitions including solid-to-solid amorphization and order-to-order phase transitions. Compared with the conventional thermal amorphization,these transitions have potential superiors such as faster speed, better endurance, and low power consumption. This article summarizes some recent progress of experimental observations and theoretical analyses on these unconventional phase transitions. The discussions mainly focus on the physical mechanism at atomic scale to provide guidance to control the phase transitions for optical storage. Outlook on some possible applications of the non-thermal phase transition is also presented to develop new types of devices.展开更多
A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silic...A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.展开更多
An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell ...An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.展开更多
Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the a...Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.展开更多
Soil in a cold region is subject to frequent freezing and thawing cycles.Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture.It is important to...Soil in a cold region is subject to frequent freezing and thawing cycles.Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture.It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage,and to devise proper mitigation measures for effective pot planting in cold regions.A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil.The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature.Microscopic poromechanic effects on heat transfer behavior were ignored.The spatial domain of the problem was simplified to a 1D spherical coordinate system with variation in the radial direction.Green's function was applied to solve for the time-dependent body temperature.Experiments were conducted for validation of the theoretical model.Reasonable agreement between the theoretical predictions and experimental measurements was obtained.The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes,e.g.,thermal properties of soil,ambient temperature,and planting pot size.展开更多
Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of...Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of the phase-change heat sink for high power （HP） light emitting diode （LED）. The experimental results show that two different structures of rectangular- and triangular-shaped micro-grooves are formed in P-E process. When P-E depth （ap）, interval of helical grooves （dp） and rotation speed （n） are 0.12 ram, 0.2 mm and 100 r/min, respectively, the boiling structures of triangular-shaped grooves with the fin height of 0.15 mm that has good evaporation performance are obtained. The shapes of the boiling structures are restricted by dp and ap, and dp is determined by n and amount of feed （f）. The ploughing speed has an important influence on the formation of groove structure in P-E process.展开更多
Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike continu...Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike continuous synaptic depression.The relatively large power consumption and poor analog behavior of PCM devices greatly limit their applications.Here,we fabricate a GeTe/Sb2Te3 superlattice-like PCM device which allows a progressive RESET process.Our devices feature low-power consumption operation and potential high-density integration,which can effectively simulate biological synaptic characteristics.The programming energy can be further reduced by properly selecting the resistance range and operating method.The fabricated devices are implemented in both artificial neural networks(ANN)and convolutional neural network(CNN)simulations,demonstrating high accuracy in brain-like pattern recognition.展开更多
Phase-change line memory cells with different line widths are fabricated using focused-ion-beam deposited C-Pt as a hard mask. The electrical performance of these memory devices was characterized. The current^oltage ...Phase-change line memory cells with different line widths are fabricated using focused-ion-beam deposited C-Pt as a hard mask. The electrical performance of these memory devices was characterized. The current^oltage （I-V） and resistance-voltage （RV） characteristics demonstrate that the power consumption decreases with the width of the phase-change line. A three-dimensional simulation is carried out to further study the scaling properties of the phase- change line memory. The results show that the resistive amorphous （RESET） power consumption is proportional to the cross-sectional area of the phase-change line, but increases as the line length decreases.展开更多
A theoretical investigation of nanosecond crystallization kinetics of the phase-change optical recording films is presented. An extended Kissinger equation for the square-root heating is derived, which properly descri...A theoretical investigation of nanosecond crystallization kinetics of the phase-change optical recording films is presented. An extended Kissinger equation for the square-root heating is derived, which properly describes the temperature evolution of the films by nanosecond laser heating. The extended Kissinger equation was used to explain our previous experimental results.展开更多
The influence of phase-change coefficients variations in the Singhal cavitation model on the calculation results has been numerically studied. By comparing the numerical results and experimental data, the relationship...The influence of phase-change coefficients variations in the Singhal cavitation model on the calculation results has been numerically studied. By comparing the numerical results and experimental data, the relationship between the coefficients and cavitation numbers is obtained. The calculation results of 2d axisymmetrical cylinder with 45-degree cone cavitator show that under different cavitation numbers, there are three typical kind of cavities, which are respectively main cavity, secondary cavity and rear cavity. The coefficients variations have a great influence respectively on the three type cavities in shape, collapse position, collapse strength, etc, and different cavitation numbers are corresponding to different phase-change coefficients. The cavitation flow field can be divided into three typical zones according to the cavitation number: weak-cavitation zone, secondary-cavitation zone and supercavitation zone. For 45-degree cone cavitator cylinder, the evaporation coefficients will firstly decrease and then increase with the decrease of cavitation numbers in secondary-cavitation zone, while the condensation coefficients keep relatively lower and almost unchanged. In weak-cavitation zone, there only exists the smaller main cavity attached to the model head or there is no obvious cavity. In supercavitation zone, the secondary cavity attached to the model will fall off and merge into the new rear cavity.展开更多
Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste ...Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.展开更多
基金financially supported by a National Research Foundation of Korea(NRF)grant funded by the Korean government(No.2016R1A3B1908249,RS202400407199).
文摘Although phase-change random-access memory(PCRAM)is a promising next-generation nonvolatile memory technology,challenges remain in terms of reducing energy consumption.This is primarily be-cause the high thermal conductivities of phase-change materials(PCMs)promote Joule heating dissi-pation.Repeated phase transitions also induce long-range atomic diffusion,limiting the durability.To address these challenges,phase-change heterostructure(PCH)devices that incorporate confinement sub-layers based on transition-metal dichalcogenide materials have been developed.In this study,we engi-neered a PCH device by integrating HfTe_(2),which has low thermal conductivity and excellent stability,into the PCM to realize PCRAM with enhanced thermal efficiency and structural stability.HEAT sim-ulations were conducted to validate the superior heat confinement in the programming region of the HfTe_(2)-based PCH device.Moreover,electrical measurements of the device demonstrated its outstanding performance,which was characterized by a low RESET current(∼1.6 mA),stable two-order ON/OFF ratio,and exceptional cycling endurance(∼2×10^(7)).The structural integrity of the HfTe_(2)confinement sub-layer was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy.The material properties,including electrical conductivity,cohesive energy,and electronegativity,substantiated these findings.Collectively,these results revealed that the HfTe_(2)-based PCH device can achieve significant improvements in performance and reliability compared with conventional PCRAM devices.
基金Supported by the National Natural Science Foundation of China(NSFC)Major Project(51991362).
文摘Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.
基金funded by the Natural Science Foundation of Heilongjiang Province,China(Grant No.PL2024E027)。
文摘The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to efficiently manage energy storage and release.This technology requires lower pressure and temperature control,resulting in reduced energy consumption and improved efficiency.Additionally,it is less restricted by geographical factors to a certain extent,enabling the formation of a closed-loop system.This contributes to the development of new energy utilization systems.The article examines and compares two experimental energy storage projects employing elastic gasbags to maintain a constant pressure supply of carbon dioxide on the low-pressure side.It further details the precise calculation methods for system cycle efficiency and energy storage density while analyzing energy losses incurred during the storage and release phases.Finally,an economic analysis is conducted using specific data,demonstrating that optimizing temperature and pressure parameters at various nodes enhances overall system efficiency while reducing energy consumption.Furthermore,the study highlights the system's high sensitivity to grid electricity prices.This research is anticipated to contribute to the development of more efficient and reliable energy storage solutions for power systems,addressing the growing energy demands and sustainability challenges.
基金supported by the Beijing Natural Science Foundation(Grant No.:2242049)。
文摘To address the limitations of conventional energy systems and optimize the energy conversion pathways and efficiency,a type of“five-in-one”multifunctional phase-change composite with magnetothermal,electrothermal,solar-thermal,and thermoelectric energy conversion and electromagnetic shielding functions is developed for multipurpose applications.Such a novel phase-change composite is fabricated by an innovative combination of paraffin wax(PW)as a phase-change material and a carbonized polyimide/Kevlar/graphene oxide@ZIF-67 complex aerogel as a supporting material.The carbonized complex aerogel exhibits a unique bidirectional porous structure with high porosity and robust skeleton to support the loading of PW.The reduced graphene oxide and Co NC resulting from high-temperature carbonization are anchored on the aerogel skeleton to generate high thermal conduction and magnetic effect,enhancing the phonon and electron transfer of the aerogel and improving its energy conversion efficiency.The phase-change composite not only exhibits excellent solar-thermal,thermoelectric,electrothermal,and magnetothermal energy conversion performance,but also achieves high electromagnetic interference shielding effectiveness of 66.2 d B in the X-band.The introduction of PW significantly improves the thermal energy-storage capacity during multi-energy conversion.The developed composite exhibits great application potential for efficient solar energy utilization,sustainable power generation,outdoor deicing,human thermal therapy,and electronic device protection.
基金the support of the National Natural Science Foundation of China(Grant No.62204201)。
文摘In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.In particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor line.Chip manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line process.In this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device performance.After a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide platforms.Next,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode operation.Finally,the fabrication of photonic and photonic–electronic neuromorphic computing systems is reviewed.These systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern recognition.With large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.
基金National Natural Science Foundation of China (50276001, 50876004)
文摘This article,based on authors＇ long-term study,proposes an improved foamed-Ni-packed phase-change thermal storage canister,which takes advantage of the foamed-Ni characteristic of instinctive porous structure and excellent properties to ameliorate its void distribution and thermal conductivity. The improved canister and the unimproved one without foamed-Ni package,are put to heat absorbing and releasing tests to investigate the effects of heat absorbing temperature upon the phase-change materials （PCM） melting time under three temperature schemes by using platinum resistance thermometers （PT100） and data acquisition modules （ADAM-4000） to gather the data of varying temperature. Afterwards,the computerized tomography （CT） is employed to scan the void distribution in both canisters. Compared to the unimproved canister,the experimental results evidence the superiority of the improved one in higher uniformity in void and temperature distribution as well as faster thermal responses.
基金the National Natural Science Foundation of China(Grant Nos.21773291,61904118,and 22002102)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190935 and BK20190947)+3 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant Nos.19KJA210005,19KJB510012,19KJB120005,and 19KJB430034)the Fund from the Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices(Grant No.SZS201812)the Science Fund from the Jiangsu Key Laboratory for Environment Functional Materialsthe State Key Laboratory of Transducer Technology,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences.
文摘The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.
文摘To investigate thermal protection effects of heat sinking vest with phase-change material （PCM）, human thermoregulation model is introduced, and a thermal mathematical model of heat transfer with phase change has been developed with the enthalpy method. The uniform energy equation is constructed for the whole domain, and the equation is implicitly discreted by control volume and finite difference method. Then the enthalpy in each node is solved by using chasing method to calculate the tridiagonal equations, and the inner surface temperature of PCM could be obtained. According to the human thermoregulation model of heat sinking vest, the dynamic temperature distribution and sweat of the body are solved. Calculation results indicate that the change of core temperature matches the experimental result, and the sweat difference is small. This thermal mathematical model of heat transfer with phase change is credible and appropriate. Through comparing the dynamic temperature distribution and sweat of the body wearing heat sinking vest to results of the body not wearing this clothing, it is evident that wearing heat sinking vest can reduce the body heat load significantly.
基金supported by the National Key Research and Development Program of China(2017YFA0206101,2017YFB0701703,2017YFA0206104,2017YFB0405601,2018YFB0407500)the National Natural Science Foundation of China(91964204,61874178,61874129)+1 种基金the Science and Technology Council of Shanghai(20501120300,18DZ2272800)the Shanghai Sailing Program(19YF1456100).
文摘Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures,which is critical for the efficient processing and reliable storage of data at full capacity.Herein,we report a novel PCM device based on Ta-doped antimony telluride(Sb2Te),which exhibits both high-speed characteristics and excellent high-temperature characteristics,with an operation speed of 2 ns,endurance of >106 cycles,and reversible switching at 140℃.The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure,which improves the thermal stability.Furthermore,the small grains in the three-dimensional limit lead to an increased energy efficiency and a reduced risk of layer segregation,reducing the power consumption and improving the long-term endurance.Our findings for this new Ta-Sb2Te material system can facilitate the development of PCMs with improved performance and novel applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61922035 and 11904118)
文摘Recent years, optically controlled phase-change memory draws intensive attention owing to some advanced applications including integrated all-optical nonvolatile memory, in-memory computing, and neuromorphic computing. The light-induced phase transition is the key for this technology. Traditional understanding on the role of light is the heating effect. Generally, the RESET operation of phase-change memory is believed to be a melt-quenching-amorphization process. However, some recent experimental and theoretical investigations have revealed that ultrafast laser can manipulate the structures of phase-change materials by non-thermal effects and induces unconventional phase transitions including solid-to-solid amorphization and order-to-order phase transitions. Compared with the conventional thermal amorphization,these transitions have potential superiors such as faster speed, better endurance, and low power consumption. This article summarizes some recent progress of experimental observations and theoretical analyses on these unconventional phase transitions. The discussions mainly focus on the physical mechanism at atomic scale to provide guidance to control the phase transitions for optical storage. Outlook on some possible applications of the non-thermal phase transition is also presented to develop new types of devices.
基金supported by the National Key Research and Development Projects(No.2018YFC0808600)。
文摘A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA09020402the National Integrate Circuit Research Program of China under Grant No 2009ZX02023-003+1 种基金the National Natural Science Foundation of China under Grant Nos 61261160500,61376006,61401444 and 61504157the Science and Technology Council of Shanghai under Grant Nos 14DZ2294900,15DZ2270900 and 14ZR1447500
文摘An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.
基金Project supported by the Natural Science Foundation of Shaanxi Province,China(Grant No.2021JM466)
文摘Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.
基金Project(No.10206014)supported by Research Grant Council Direct Allocation Fund from the University of Hong Kong,China
文摘Soil in a cold region is subject to frequent freezing and thawing cycles.Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture.It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage,and to devise proper mitigation measures for effective pot planting in cold regions.A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil.The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature.Microscopic poromechanic effects on heat transfer behavior were ignored.The spatial domain of the problem was simplified to a 1D spherical coordinate system with variation in the radial direction.Green's function was applied to solve for the time-dependent body temperature.Experiments were conducted for validation of the theoretical model.Reasonable agreement between the theoretical predictions and experimental measurements was obtained.The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes,e.g.,thermal properties of soil,ambient temperature,and planting pot size.
基金Projects(50436010, 50675070) supported by the National Natural Science Foundation of China Project(07118064) supported by the Natural Science Foundation of Guangdong Province, China+1 种基金 Project(U0834002) supported by the Joint Fund of NSFC-Guangdong of ChinaProjects(SY200806300289A, JSA200903190981A) supported by Shenzhen Scientific Program, China
文摘Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of the phase-change heat sink for high power （HP） light emitting diode （LED）. The experimental results show that two different structures of rectangular- and triangular-shaped micro-grooves are formed in P-E process. When P-E depth （ap）, interval of helical grooves （dp） and rotation speed （n） are 0.12 ram, 0.2 mm and 100 r/min, respectively, the boiling structures of triangular-shaped grooves with the fin height of 0.15 mm that has good evaporation performance are obtained. The shapes of the boiling structures are restricted by dp and ap, and dp is determined by n and amount of feed （f）. The ploughing speed has an important influence on the formation of groove structure in P-E process.
基金Project supported by the National Science and Technology Major Project of China(Grant No.2017ZX02301007-002)the National Key R&D Plan of China(Grant No.2017YFB0701701)the National Natural Science Foundation of China(Grant Nos.61774068 and 51772113).The authors acknowledge the support from Hubei Key Laboratory of Advanced Memories&Hubei Engineering Research Center on Microelectronics.
文摘Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike continuous synaptic depression.The relatively large power consumption and poor analog behavior of PCM devices greatly limit their applications.Here,we fabricate a GeTe/Sb2Te3 superlattice-like PCM device which allows a progressive RESET process.Our devices feature low-power consumption operation and potential high-density integration,which can effectively simulate biological synaptic characteristics.The programming energy can be further reduced by properly selecting the resistance range and operating method.The fabricated devices are implemented in both artificial neural networks(ANN)and convolutional neural network(CNN)simulations,demonstrating high accuracy in brain-like pattern recognition.
基金Project supported by the National Integrate Circuit Research Program of China (Grant No. 2009ZX02023-003)the National Key Basic Research Program of China (Grant Nos. 2010CB934300, 2011CBA00602, and 2011CB932800)+1 种基金the National Natural Science Foundation of China (Grant Nos. 60906003, 60906004, 61006087, and 61076121)the Science and Technology Council of Shanghai of China (Grant No. 1052nm07000)
文摘Phase-change line memory cells with different line widths are fabricated using focused-ion-beam deposited C-Pt as a hard mask. The electrical performance of these memory devices was characterized. The current^oltage （I-V） and resistance-voltage （RV） characteristics demonstrate that the power consumption decreases with the width of the phase-change line. A three-dimensional simulation is carried out to further study the scaling properties of the phase- change line memory. The results show that the resistive amorphous （RESET） power consumption is proportional to the cross-sectional area of the phase-change line, but increases as the line length decreases.
基金Project supported by the Natural Science Foundation of Heilongjiang Province, China and the Foundation of Harbin Institute of Technology, China.
文摘A theoretical investigation of nanosecond crystallization kinetics of the phase-change optical recording films is presented. An extended Kissinger equation for the square-root heating is derived, which properly describes the temperature evolution of the films by nanosecond laser heating. The extended Kissinger equation was used to explain our previous experimental results.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51149003)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2013033)
文摘The influence of phase-change coefficients variations in the Singhal cavitation model on the calculation results has been numerically studied. By comparing the numerical results and experimental data, the relationship between the coefficients and cavitation numbers is obtained. The calculation results of 2d axisymmetrical cylinder with 45-degree cone cavitator show that under different cavitation numbers, there are three typical kind of cavities, which are respectively main cavity, secondary cavity and rear cavity. The coefficients variations have a great influence respectively on the three type cavities in shape, collapse position, collapse strength, etc, and different cavitation numbers are corresponding to different phase-change coefficients. The cavitation flow field can be divided into three typical zones according to the cavitation number: weak-cavitation zone, secondary-cavitation zone and supercavitation zone. For 45-degree cone cavitator cylinder, the evaporation coefficients will firstly decrease and then increase with the decrease of cavitation numbers in secondary-cavitation zone, while the condensation coefficients keep relatively lower and almost unchanged. In weak-cavitation zone, there only exists the smaller main cavity attached to the model head or there is no obvious cavity. In supercavitation zone, the secondary cavity attached to the model will fall off and merge into the new rear cavity.
文摘Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.
