Rare earth high-entropy alloys(RE-HEAs)exhibit great potential to be applied as refrigerants due to their good comprehensive magnetocaloric properties.In this work,octary GdTbDyHoErTmCoAl and GdTbDyHoErTmCoNi RE-HEAs ...Rare earth high-entropy alloys(RE-HEAs)exhibit great potential to be applied as refrigerants due to their good comprehensive magnetocaloric properties.In this work,octary GdTbDyHoErTmCoAl and GdTbDyHoErTmCoNi RE-HEAs with amorphous/nanocrystalline structure exhibiting comparable magnetocaloric effect were synthesized.Both RE-HEAs show a second-order magnetic phase transition in the temperature range of hydrogen liquefaction.Due to the complex magnetic interactions,a spin glasslike behavior at low temperatures is observed in the RE-HEAs.A superior magnetocaloric effect is obtained in the nanocrystalline GdTbDyHoErTmCoNi high-entropy alloy that is multiphase attributed to a stronger magnetic exchange interaction when compared with the other that exhibits single amorphous structure.Despite heterogeneous microstructure,homogeneous chemical distributions are observed in the partially crystallized high-entropy alloy.In addition,the magnetocaloric effect and magnetic transition behavior of rare earth medium-and high-entropy alloys,including the RE-HEAs in this study,are summarized and discussed.The results in this work provide a helpful guide for the design of RE-HEAs for hydrogen liquefaction applications with excellent magnetocaloric effects.展开更多
Heavy ion irradiation effects on charge trapping memory(CTM)capacitors with TiN/Al_(2)O_(3)/HfO_(2)/Al_(2)O_(3)/HfO_(2)/SiO_(2)/p-Si structure have been investigated.The ion-induced interface charges and oxide trap ch...Heavy ion irradiation effects on charge trapping memory(CTM)capacitors with TiN/Al_(2)O_(3)/HfO_(2)/Al_(2)O_(3)/HfO_(2)/SiO_(2)/p-Si structure have been investigated.The ion-induced interface charges and oxide trap charges were calculated and analyzed by capacitance-voltage(C-V)characteristics.The C-V curves shift towards the negative direction after swift heavy ion irradiation,due to the net positive charges accumulating in the trapping layer.The memory window decreases with the increase of ion fluence at high voltage,which results from heavy ion-induced structural damage in the blocking layer.The mechanism of heavy ion irradiation effects on CTM capacitors is discussed in detail with energy band diagrams.The results may help to better understand the physical mechanism of heavy ion-induced degradation of CTM capacitors.展开更多
Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we r...Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we report the enhancement in the room-temperature plasticity during the compression(25%)and bending flexibility of Fe_(74)Mo_(6)P_(13)C_(7) FBMG by using water quenching.The high-energy synchrotron X-ray measurements,high-resolution transmission electron microscopy,three-dimensional X-ray microtomog-raphy,and finite element simulation were performed to reveal the origin.It was found that the M-shape profile of residual stress improves the mechanical properties of FBMGs,particularly their plasticity.The reversal of the heat-transfer coefficient and cooling rate from the'vapor blanket'to'nucleate boiling'transition during water quenching processing is the main cause of the unusual profile of residual stress in glassy cylinders.Encouraged by the progress in developing flexible silicate glasses,this work highlights a processing method to improve plasticity and surmount technical barriers for the commercialization of FBMGs.展开更多
Soft magnetic composites(SMCs)play a pivotal role in the development of high-frequency,miniaturization and complex forming of modern electronics.However,they usually suffer from a trade-off between high magnetization ...Soft magnetic composites(SMCs)play a pivotal role in the development of high-frequency,miniaturization and complex forming of modern electronics.However,they usually suffer from a trade-off between high magnetization and good magnetic softness(high permeability and low core loss).In this work,utilizing the order modulation strategy,a critical state in a FeSiBCCr amorphous soft magnetic composite(ASMC),consisting of massive crystal-like orders(CLOs,∼1 nm in size)with the feature ofα-Fe,is designed.This critical-state structure endows the amorphous powder with the enhanced ferromagnetic exchange interactions and the optimized magnetic domains with uniform orientation and fewer micro-vortex dots.Superior comprehensive soft magnetic properties at high frequency emerge in the ASMC,such as a high saturation magnetization(Ms)of 170 emu g^(-1)and effective permeability(µ_(e))of 65 combined with a core loss(Pcv)as low as 70 mW cm^(-3)(0.01 T,1 MHz).This study provides a new strategy for the development of high-frequency ASMCs,possessing suitable comprehensive soft magnetic performance to match the requirements of the modern magnetic devices used in the third-generation semiconductors and new energy fields.展开更多
基金Project supported by the National Natural Science Foundation of China(52101193,51975183)China Postdoctoral Science Foundation(2022M711002)+2 种基金Fundamental Research Funds for the Central Universities(B220202036)the Natural Science Foundation of Jiangsu Province(BK20201316)Jiangsu Planned Projects for Postdoctoral Research Funds(2021K646C)。
文摘Rare earth high-entropy alloys(RE-HEAs)exhibit great potential to be applied as refrigerants due to their good comprehensive magnetocaloric properties.In this work,octary GdTbDyHoErTmCoAl and GdTbDyHoErTmCoNi RE-HEAs with amorphous/nanocrystalline structure exhibiting comparable magnetocaloric effect were synthesized.Both RE-HEAs show a second-order magnetic phase transition in the temperature range of hydrogen liquefaction.Due to the complex magnetic interactions,a spin glasslike behavior at low temperatures is observed in the RE-HEAs.A superior magnetocaloric effect is obtained in the nanocrystalline GdTbDyHoErTmCoNi high-entropy alloy that is multiphase attributed to a stronger magnetic exchange interaction when compared with the other that exhibits single amorphous structure.Despite heterogeneous microstructure,homogeneous chemical distributions are observed in the partially crystallized high-entropy alloy.In addition,the magnetocaloric effect and magnetic transition behavior of rare earth medium-and high-entropy alloys,including the RE-HEAs in this study,are summarized and discussed.The results in this work provide a helpful guide for the design of RE-HEAs for hydrogen liquefaction applications with excellent magnetocaloric effects.
基金the National Natural Science Foundation of China(Grant Nos.12105340,12035019,and12075290)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020412)。
文摘Heavy ion irradiation effects on charge trapping memory(CTM)capacitors with TiN/Al_(2)O_(3)/HfO_(2)/Al_(2)O_(3)/HfO_(2)/SiO_(2)/p-Si structure have been investigated.The ion-induced interface charges and oxide trap charges were calculated and analyzed by capacitance-voltage(C-V)characteristics.The C-V curves shift towards the negative direction after swift heavy ion irradiation,due to the net positive charges accumulating in the trapping layer.The memory window decreases with the increase of ion fluence at high voltage,which results from heavy ion-induced structural damage in the blocking layer.The mechanism of heavy ion irradiation effects on CTM capacitors is discussed in detail with energy band diagrams.The results may help to better understand the physical mechanism of heavy ion-induced degradation of CTM capacitors.
基金National Natural Science Foundation of China(No.52171165)。
文摘Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we report the enhancement in the room-temperature plasticity during the compression(25%)and bending flexibility of Fe_(74)Mo_(6)P_(13)C_(7) FBMG by using water quenching.The high-energy synchrotron X-ray measurements,high-resolution transmission electron microscopy,three-dimensional X-ray microtomog-raphy,and finite element simulation were performed to reveal the origin.It was found that the M-shape profile of residual stress improves the mechanical properties of FBMGs,particularly their plasticity.The reversal of the heat-transfer coefficient and cooling rate from the'vapor blanket'to'nucleate boiling'transition during water quenching processing is the main cause of the unusual profile of residual stress in glassy cylinders.Encouraged by the progress in developing flexible silicate glasses,this work highlights a processing method to improve plasticity and surmount technical barriers for the commercialization of FBMGs.
基金Guangdong Major Project of Basic and Applied Basic Research,China(Grant No.2019B030302010)the National Natural Science Foundation of China(Grant Nos.52301212,52071222,52101191,52001219)+1 种基金the National Key Research and Development Program of China(Grant No.2021YFA0716302)Guangdong Basic and Applied Basic Research,China(Grant Nos.2022A1515010347,2020B1515130007).
文摘Soft magnetic composites(SMCs)play a pivotal role in the development of high-frequency,miniaturization and complex forming of modern electronics.However,they usually suffer from a trade-off between high magnetization and good magnetic softness(high permeability and low core loss).In this work,utilizing the order modulation strategy,a critical state in a FeSiBCCr amorphous soft magnetic composite(ASMC),consisting of massive crystal-like orders(CLOs,∼1 nm in size)with the feature ofα-Fe,is designed.This critical-state structure endows the amorphous powder with the enhanced ferromagnetic exchange interactions and the optimized magnetic domains with uniform orientation and fewer micro-vortex dots.Superior comprehensive soft magnetic properties at high frequency emerge in the ASMC,such as a high saturation magnetization(Ms)of 170 emu g^(-1)and effective permeability(µ_(e))of 65 combined with a core loss(Pcv)as low as 70 mW cm^(-3)(0.01 T,1 MHz).This study provides a new strategy for the development of high-frequency ASMCs,possessing suitable comprehensive soft magnetic performance to match the requirements of the modern magnetic devices used in the third-generation semiconductors and new energy fields.
