Piezoelectric energy harvesters(PEHs)have attracted significant attention with the ability of converting mechanical energy into electrical energy and power the self-powered microelectronic components.Generally,materia...Piezoelectric energy harvesters(PEHs)have attracted significant attention with the ability of converting mechanical energy into electrical energy and power the self-powered microelectronic components.Generally,material's superior energy harvesting performance is closely related to its high transduction coefficient(d_(33)×g_(33)),which is dependent on higher piezoelectric coefficient d33 and lower dielectric constantεr of materials.However,the high d33 and lowεr are difficult to be simultaneously achieved in piezoelectric ceramics.Herein,lead zirconate titanate(PZT)based piezoelectric composites with vertically aligned microchannel structure are constructed by phase-inversion method.The polyvinylidene fluoride(PVDF)and carbon nanotubes(CNTs)are mixed as fillers to fabricate PZT/PVDF&CNTs composites.The unique structure and uniformly distributed CNTs network enhance the polarization and thus improve the d33.The PVDF filler effectively reduce theεr.As a consequence,the excellent piezoelectric coefficient(d_(33)=595 pC/N)and relatively low dielectric constant(ε_(r)=1,603)were obtained in PZT/PVDF&CNTs composites,which generated an ultra-high d_(33)×g_(33) of 24,942×10^(−15) m^(2)/N.Therefore,the PZT/PVDF&CNTs piezoelectric composites achieve excellent energy harvesting performance(output voltage:66 V,short current:39.22μA,and power density:1.25μW/mm^(2)).Our strategy effectively boosts the performance of piezoelectric-polymer composites,which has certain guiding significance for design of energy harvesters.展开更多
The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the excepti...The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the exceptional electrical properties in harsh environments can further promote their practical applications.Defect carriers can be excited under luminance irradiation,thereby leading to degradation of energy storage performance.Herein,a synergic optimization strategy is proposed to enhance energy storage properties and luminance resistance of(K_(0.5)Na_(0.5))NbO_(3)-base(KNN)ceramics.First,the introduction of Bi(Zn0.5Ti0.5)O_(3) solid solution and La3+ions disrupts the long-range polar orders and enhances super paraelectric relaxation characteristics.Additionally,doping La3+ions can increase the band gap and reduce oxygen vacancy concentration,resulting in excellent luminance resistance.Finally,the viscous polymer process is employed to suppress the grain growth and promote chemical homogeneity.As a result,ultrahigh recoverable energy storage density(Wrec)of 8.11 J/cm3 and high efficiency(η)of 80.98%are achieved under an electric field of 568 kV/cm.Moreover,the variations in Wrec andηare only 12.45%and 1.75%,respectively,under 500 W xenon lamp irradiation compared to the performance under a dark environment.These findings hold great potential in facilitating the practical application of dielectric ceramic capacitors in luminance irradiation environments.展开更多
With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recen...With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.展开更多
Irrigation consumes three quarters of globalwater withdrawals each year. Strategies are needed toreduce irrigationwater use, including increasingtheefficiency of transfer methods and field application.Comprehensive re...Irrigation consumes three quarters of globalwater withdrawals each year. Strategies are needed toreduce irrigationwater use, including increasingtheefficiency of transfer methods and field application.Comprehensive restoration of soil health, specificallythrough organic matter amendments, can substantiallyreduce irrigation demand and increase crop yield. Aprogram to restore severely degraded and desertified soilsby incorporating coarse woodchips into the soil success-fully increased rainfall capture and elevated soil moisturefor several weeks between rainfall events at both Ningxia,north-west China and North Dakota, USA. With additionof fertilizer, woodchip incorporation further increasedgrowth of wheat and alfalfa. Comprehensive soil healthassessment of remnant grasslands was used to developtarget reference soil profiles by which to guide restorationefforts. Given that most agricultural soils are degraded tosome degree, soil health restoration can provide a powerfulstrategy toward achieving global food and water security.展开更多
基金The work was supported by the National Natural Science Foundation of China(Grant No.52072150 and 51972146)Shandong Province Key Fundamental Research Program(Grant No.ZR2022ZD39)Beijing Natural Science Foundation(Grant No.JL23004).
文摘Piezoelectric energy harvesters(PEHs)have attracted significant attention with the ability of converting mechanical energy into electrical energy and power the self-powered microelectronic components.Generally,material's superior energy harvesting performance is closely related to its high transduction coefficient(d_(33)×g_(33)),which is dependent on higher piezoelectric coefficient d33 and lower dielectric constantεr of materials.However,the high d33 and lowεr are difficult to be simultaneously achieved in piezoelectric ceramics.Herein,lead zirconate titanate(PZT)based piezoelectric composites with vertically aligned microchannel structure are constructed by phase-inversion method.The polyvinylidene fluoride(PVDF)and carbon nanotubes(CNTs)are mixed as fillers to fabricate PZT/PVDF&CNTs composites.The unique structure and uniformly distributed CNTs network enhance the polarization and thus improve the d33.The PVDF filler effectively reduce theεr.As a consequence,the excellent piezoelectric coefficient(d_(33)=595 pC/N)and relatively low dielectric constant(ε_(r)=1,603)were obtained in PZT/PVDF&CNTs composites,which generated an ultra-high d_(33)×g_(33) of 24,942×10^(−15) m^(2)/N.Therefore,the PZT/PVDF&CNTs piezoelectric composites achieve excellent energy harvesting performance(output voltage:66 V,short current:39.22μA,and power density:1.25μW/mm^(2)).Our strategy effectively boosts the performance of piezoelectric-polymer composites,which has certain guiding significance for design of energy harvesters.
基金supported by the National Natural Science Foundation of China(Grant Nos.52072150 and 51972146)Shandong Province Key Fundamental Research Program(Grant No.ZR2022ZD39).
文摘The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the exceptional electrical properties in harsh environments can further promote their practical applications.Defect carriers can be excited under luminance irradiation,thereby leading to degradation of energy storage performance.Herein,a synergic optimization strategy is proposed to enhance energy storage properties and luminance resistance of(K_(0.5)Na_(0.5))NbO_(3)-base(KNN)ceramics.First,the introduction of Bi(Zn0.5Ti0.5)O_(3) solid solution and La3+ions disrupts the long-range polar orders and enhances super paraelectric relaxation characteristics.Additionally,doping La3+ions can increase the band gap and reduce oxygen vacancy concentration,resulting in excellent luminance resistance.Finally,the viscous polymer process is employed to suppress the grain growth and promote chemical homogeneity.As a result,ultrahigh recoverable energy storage density(Wrec)of 8.11 J/cm3 and high efficiency(η)of 80.98%are achieved under an electric field of 568 kV/cm.Moreover,the variations in Wrec andηare only 12.45%and 1.75%,respectively,under 500 W xenon lamp irradiation compared to the performance under a dark environment.These findings hold great potential in facilitating the practical application of dielectric ceramic capacitors in luminance irradiation environments.
基金supported by the National Natural Science Foundation of China(Grant No.52072150)the Young Elite Scientists Sponsorship Program of the Chinese Academy of Space Technology(CAST)and Open Foundation of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices(EFMD2021002Z).
文摘With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.
文摘Irrigation consumes three quarters of globalwater withdrawals each year. Strategies are needed toreduce irrigationwater use, including increasingtheefficiency of transfer methods and field application.Comprehensive restoration of soil health, specificallythrough organic matter amendments, can substantiallyreduce irrigation demand and increase crop yield. Aprogram to restore severely degraded and desertified soilsby incorporating coarse woodchips into the soil success-fully increased rainfall capture and elevated soil moisturefor several weeks between rainfall events at both Ningxia,north-west China and North Dakota, USA. With additionof fertilizer, woodchip incorporation further increasedgrowth of wheat and alfalfa. Comprehensive soil healthassessment of remnant grasslands was used to developtarget reference soil profiles by which to guide restorationefforts. Given that most agricultural soils are degraded tosome degree, soil health restoration can provide a powerfulstrategy toward achieving global food and water security.
