Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu...Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu_(0.2) high-entropy alloy powders(HEAs)with both large aspect ratios and thin intergranular amorphous layers are constructed by a multistage mechanical alloying strategy,aiming to achieve excellent and temperature-stable permeability and EMW absorption.A single-phase face-centered cubic structure with good ductility and high crystallinity is obtained as wet milling precursors,via precisely controlling dry milling time.Then,HEAs are flattened to improve aspect ratios by synergistically regulating wet milling time.FeCoNiCr_(0.4)Cu_(0.2) HEAs with dry milling 20 h and wet milling 5 h(D20)exhibit higher and more stable permeability because of larger aspect ratios and thinner intergranular amorphous layers.The maximum reflection loss(RL)of D20/SiO_(2) composites is greater than-7 dB with 5 mm thickness,and EMW absorption bandwidth(RL<-7 dB)can maintain between 523 and 600 MHz from-50 to 150℃.Furthermore,relying on the“cocktail effect”of HEAs,D20 sample also exhibits excellent corrosion resistance and high Curie temperature.This work provides a facile and tunable strategy to design MHz electromagnetic absorbers with temperature stability,broadband,and resistance to harsh environments.展开更多
A flexible and stable power supply is essential to the rapid development of wearable electronic devices.In this work,a transparent,flexible,temperature-stable and ionogel electrode-based self-healing triboelectric nan...A flexible and stable power supply is essential to the rapid development of wearable electronic devices.In this work,a transparent,flexible,temperature-stable and ionogel electrode-based self-healing triboelectric nanogenerator(IS-TENG)was developed.The ionogel with excellent stretchability(1,012%),high ionic conductivity(0.3 S·m^(−1))and high-temperature stability(temperature range of−77 to 250℃)was used as the electrode of the IS-TENG.The IS-TENG exhibited excellent transparency(92.1%)and stability.The output performance did not decrease when placed in a 60℃oven for 48 h.In addition,the IS-TENG behaved like a stable output in the range of−20 to 60℃.More importantly,the IS-TENG could also achieve self-healing of electrical performance at temperatures between−20 and 60℃and its output can be restored to its original state after healing.When the single-electrode IS-TENG with an area of 3 cm×3 cm was conducted under the working frequency of 1.5 Hz,the output values for open-circuit voltage,short-circuit current,short-circuit transferred charge,and maximum peak power density were 189 V,6.2μA,57 nC,and 2.17 W·m^(−2),respectively.The IS-TENG enables to harvest biomechanical energy,and drive electronic devices.Furthermore,the application of IS-TENGs as self-driven sensors for detecting human behavior was also demonstrated,showing good application prospects in the field of wearable power technology and self-driven sensing.展开更多
Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaT...Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaTiO_(3)ceramics,an excellent piezoelectric constant(d33)of 325 pC/N was achieved by applying a novel poling method(AC-biasþDC-bias)with a high TC of 455℃.In addition,an ultrahigh normalized piezoelectric strain(d33*¼Smax/Emax)of 808 pm/V was obtained at the normal/typical and relaxor-ferroelectrics phase boundary simultaneously with good thermal stability(Dd33*(T)z 20%)in the temperature range of 25e125℃.The piezoelectric force microscopy results show the domain miniaturization from micro to nanoscale/polar nano-regions due to local structure heterogeneity caused by Nd doping.The mechanism for the giant piezoelectric strain is attributed to the thermal quenching,nano-domains,and reverse switching of the short-range order to the long-range order under the applied electric field.The strategic design of domain engineering and a proposed model for the high piezoelectricity is successfully supported by the phenomenological relation and Gibbs free energy profile.In this work,a new lead-free single-element modified BiFeO_(3)-BaTiO_(3)ceramics was developed by applying a synergistic approach of domain engineering and phase boundary for the high-temperature piezoelectric performance.展开更多
基金the Supported by Program for the National Natural Science Foundation of China(No.52071053,U1704253,52103334)China Postdoctoral Science Foundation(2020M670748,2020M680946)the Fundamental Research Funds for the Central Universities(DUT20GF111).
文摘Developing megahertz(MHz)electromagnetic wave(EMW)absorption materials with broadband absorption,multi-temperature adaptability,and facile preparation method remains a challenge.Herein,nanocrystalline FeCoNiCr_(0.4)Cu_(0.2) high-entropy alloy powders(HEAs)with both large aspect ratios and thin intergranular amorphous layers are constructed by a multistage mechanical alloying strategy,aiming to achieve excellent and temperature-stable permeability and EMW absorption.A single-phase face-centered cubic structure with good ductility and high crystallinity is obtained as wet milling precursors,via precisely controlling dry milling time.Then,HEAs are flattened to improve aspect ratios by synergistically regulating wet milling time.FeCoNiCr_(0.4)Cu_(0.2) HEAs with dry milling 20 h and wet milling 5 h(D20)exhibit higher and more stable permeability because of larger aspect ratios and thinner intergranular amorphous layers.The maximum reflection loss(RL)of D20/SiO_(2) composites is greater than-7 dB with 5 mm thickness,and EMW absorption bandwidth(RL<-7 dB)can maintain between 523 and 600 MHz from-50 to 150℃.Furthermore,relying on the“cocktail effect”of HEAs,D20 sample also exhibits excellent corrosion resistance and high Curie temperature.This work provides a facile and tunable strategy to design MHz electromagnetic absorbers with temperature stability,broadband,and resistance to harsh environments.
基金the financial support of the National Science Foundation of China(Nos.51605109 and 61804103)the Guangxi Natural Science Foundation(Nos.2018GXNSFBA281052 and 2018GXNSFAA281296)China Postdoctoral Science Foundation(Nos.2017M610346 and 2021T140494)。
文摘A flexible and stable power supply is essential to the rapid development of wearable electronic devices.In this work,a transparent,flexible,temperature-stable and ionogel electrode-based self-healing triboelectric nanogenerator(IS-TENG)was developed.The ionogel with excellent stretchability(1,012%),high ionic conductivity(0.3 S·m^(−1))and high-temperature stability(temperature range of−77 to 250℃)was used as the electrode of the IS-TENG.The IS-TENG exhibited excellent transparency(92.1%)and stability.The output performance did not decrease when placed in a 60℃oven for 48 h.In addition,the IS-TENG behaved like a stable output in the range of−20 to 60℃.More importantly,the IS-TENG could also achieve self-healing of electrical performance at temperatures between−20 and 60℃and its output can be restored to its original state after healing.When the single-electrode IS-TENG with an area of 3 cm×3 cm was conducted under the working frequency of 1.5 Hz,the output values for open-circuit voltage,short-circuit current,short-circuit transferred charge,and maximum peak power density were 189 V,6.2μA,57 nC,and 2.17 W·m^(−2),respectively.The IS-TENG enables to harvest biomechanical energy,and drive electronic devices.Furthermore,the application of IS-TENGs as self-driven sensors for detecting human behavior was also demonstrated,showing good application prospects in the field of wearable power technology and self-driven sensing.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3807404),Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)and the State Key Laboratory of Powder Metallurgy.Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents(Grant No.BX2021377).
文摘Lead-free BiFeO_(3)-BaTiO_(3)ceramics attract widespread attention over the last two decades due to their high Curie temperature(TC)and excellent piezoelectric performance.Here,in the Nd-modified 0.67BiFeO_(3)-0.33BaTiO_(3)ceramics,an excellent piezoelectric constant(d33)of 325 pC/N was achieved by applying a novel poling method(AC-biasþDC-bias)with a high TC of 455℃.In addition,an ultrahigh normalized piezoelectric strain(d33*¼Smax/Emax)of 808 pm/V was obtained at the normal/typical and relaxor-ferroelectrics phase boundary simultaneously with good thermal stability(Dd33*(T)z 20%)in the temperature range of 25e125℃.The piezoelectric force microscopy results show the domain miniaturization from micro to nanoscale/polar nano-regions due to local structure heterogeneity caused by Nd doping.The mechanism for the giant piezoelectric strain is attributed to the thermal quenching,nano-domains,and reverse switching of the short-range order to the long-range order under the applied electric field.The strategic design of domain engineering and a proposed model for the high piezoelectricity is successfully supported by the phenomenological relation and Gibbs free energy profile.In this work,a new lead-free single-element modified BiFeO_(3)-BaTiO_(3)ceramics was developed by applying a synergistic approach of domain engineering and phase boundary for the high-temperature piezoelectric performance.
