采用固相烧结法制备铋层结构Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0~0.20)压电陶瓷。采用X射线衍射、扫描电镜和自动控温测试系统研究Ta 5+的B位掺杂对NBT-Ta-x陶瓷的微观结构、电导、介电和压电性能的影响。结果表明:随T...采用固相烧结法制备铋层结构Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0~0.20)压电陶瓷。采用X射线衍射、扫描电镜和自动控温测试系统研究Ta 5+的B位掺杂对NBT-Ta-x陶瓷的微观结构、电导、介电和压电性能的影响。结果表明:随Ta掺杂量的增加,晶粒尺寸和长径比逐渐减小,表现出沿c轴的取向生长,同时,陶瓷的理论密度和体积密度增加,在掺杂量x=0.05时达到最高的相对密度96.1%,Ta在NBT晶格中的固溶极限在0.10附近。随Ta 5+掺杂量x增加到0.20,陶瓷的居里温度从680℃降至658℃。Ta 5+掺杂使NBT-Ta-x陶瓷的电阻率增加了两个数量级,压电常数d 33从13.8 pC/N增加到23 pC/N。当x=0.04~0.05时,NBT-Ta-x陶瓷的综合电性能良好:T c=670~672℃,d 33=21.8~23 pC/N,k p=7.9%~8.3%。展开更多
The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in ...The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in the conventional cathodes very slow,resulting in a lack of appropriate electrode materials for RMBs.In this work,we enlarge the layer spacing of V2Os by introducing Na^2+in the crystal structure to promote the diffusion kinetics of Mg^2+.The NaVeO15(NVO)synthesized by a facile method is studied as a cathode material for RMBs with the anhydrous pure Mg^2+electrolyte.As a result,the NVO not only exhibits high discharge capacity(119.2 mAh:g^-1 after 100 cycles at the current density of 20 mA:g^-1)and working voltage(above 1.6 V vs.Mg^2+/Mg),but also expresses good rate capability.Besides,the eX-situ characterizations results reveal that the Mg^2+storage mechanism in NVO is based on the intercalation and deintercalation.The density functional theory(DFT)calculation results further indicate that Mg^2+tends to occupy the semi-occupied sites of Na^+in the NVO.Moreover,the galvanostatic intermittent titration technique(GITT)demonstrates that NVO electrode has the fast diffusion kinetics of Mg^2+during discharge process ranging from 7.55×10^-13 to2.41×10^-11 cm^2·s^-1.Our work proves that the NVO is a potential cathode material for RMBs.展开更多
Y2 Mo4 O15 particles were prepared using a simple solution method（SSM） and used as a highly efficient selective adsorbent for methylene blue（MB） in aqueous solutions. The maximum adsorption capacity of the samples...Y2 Mo4 O15 particles were prepared using a simple solution method（SSM） and used as a highly efficient selective adsorbent for methylene blue（MB） in aqueous solutions. The maximum adsorption capacity of the samples was determined based on the adsorption isotherms with different adsorbent doses at 298,318 and 338 K. The fittings of the temperature-dependent isotherms yield ΔrGm^θ=-34.1 kJ/mol,ΔrHm^θ-36.9 kJ/mol and ΔrSm^θ=-9.67 J/mol·K. The as-prepared Y2 Mo4 O15 has a very large maximum adsorption capacity（i.e., 198 mg/g） for MB at room temperature, and this value is only less than that of amorphous hardwood powder. Notably, 80 mg of adsorbent is able to completely decolorize 250 mL of 30 mg/L MB aqueous solution. The kinetic parameters of the adsorption process were obtained from the temperature-dependent adsorption isotherm（i.e., E1=26.9 kJ/mol and E1 = 63.8 kJ/mol）. The results of adsorption kinetics show that it is a pseudo-second-order reaction. The mechanism of the high selectivity and the large adsorption capacity is discussed based on competitive ion（CI） experiments and coordination theory.展开更多
文摘采用固相烧结法制备铋层结构Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0~0.20)压电陶瓷。采用X射线衍射、扫描电镜和自动控温测试系统研究Ta 5+的B位掺杂对NBT-Ta-x陶瓷的微观结构、电导、介电和压电性能的影响。结果表明:随Ta掺杂量的增加,晶粒尺寸和长径比逐渐减小,表现出沿c轴的取向生长,同时,陶瓷的理论密度和体积密度增加,在掺杂量x=0.05时达到最高的相对密度96.1%,Ta在NBT晶格中的固溶极限在0.10附近。随Ta 5+掺杂量x增加到0.20,陶瓷的居里温度从680℃降至658℃。Ta 5+掺杂使NBT-Ta-x陶瓷的电阻率增加了两个数量级,压电常数d 33从13.8 pC/N增加到23 pC/N。当x=0.04~0.05时,NBT-Ta-x陶瓷的综合电性能良好:T c=670~672℃,d 33=21.8~23 pC/N,k p=7.9%~8.3%。
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.21875198 and 21621091).
文摘The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in the conventional cathodes very slow,resulting in a lack of appropriate electrode materials for RMBs.In this work,we enlarge the layer spacing of V2Os by introducing Na^2+in the crystal structure to promote the diffusion kinetics of Mg^2+.The NaVeO15(NVO)synthesized by a facile method is studied as a cathode material for RMBs with the anhydrous pure Mg^2+electrolyte.As a result,the NVO not only exhibits high discharge capacity(119.2 mAh:g^-1 after 100 cycles at the current density of 20 mA:g^-1)and working voltage(above 1.6 V vs.Mg^2+/Mg),but also expresses good rate capability.Besides,the eX-situ characterizations results reveal that the Mg^2+storage mechanism in NVO is based on the intercalation and deintercalation.The density functional theory(DFT)calculation results further indicate that Mg^2+tends to occupy the semi-occupied sites of Na^+in the NVO.Moreover,the galvanostatic intermittent titration technique(GITT)demonstrates that NVO electrode has the fast diffusion kinetics of Mg^2+during discharge process ranging from 7.55×10^-13 to2.41×10^-11 cm^2·s^-1.Our work proves that the NVO is a potential cathode material for RMBs.
基金Project supported by the Fundamental Research Funds for the Central Universities(N162302001)the Basic Key Program of Applied Basic Research of Science and Technology Commission Foundation of Hebei Province in China(15961005D)+2 种基金the Natural Science Foundation of Liaoning Province(2015020665)the Hebei Province Higher Education Research Project(ZD2017309)Northeastern University at Qinhuangdao Campus Research Fund(XNK201602)
文摘Y2 Mo4 O15 particles were prepared using a simple solution method（SSM） and used as a highly efficient selective adsorbent for methylene blue（MB） in aqueous solutions. The maximum adsorption capacity of the samples was determined based on the adsorption isotherms with different adsorbent doses at 298,318 and 338 K. The fittings of the temperature-dependent isotherms yield ΔrGm^θ=-34.1 kJ/mol,ΔrHm^θ-36.9 kJ/mol and ΔrSm^θ=-9.67 J/mol·K. The as-prepared Y2 Mo4 O15 has a very large maximum adsorption capacity（i.e., 198 mg/g） for MB at room temperature, and this value is only less than that of amorphous hardwood powder. Notably, 80 mg of adsorbent is able to completely decolorize 250 mL of 30 mg/L MB aqueous solution. The kinetic parameters of the adsorption process were obtained from the temperature-dependent adsorption isotherm（i.e., E1=26.9 kJ/mol and E1 = 63.8 kJ/mol）. The results of adsorption kinetics show that it is a pseudo-second-order reaction. The mechanism of the high selectivity and the large adsorption capacity is discussed based on competitive ion（CI） experiments and coordination theory.
