t To investigate the effect of Nb on the dehydro- genation properties of Mg-Nb composite films, Mg/Nb eight- layer film and Mg- 10 at% Nb alloy film with the similar Mg- to-Nb atomic ratio were prepared by magnetron s...t To investigate the effect of Nb on the dehydro- genation properties of Mg-Nb composite films, Mg/Nb eight- layer film and Mg- 10 at% Nb alloy film with the similar Mg- to-Nb atomic ratio were prepared by magnetron sputtering. Results show that both Mg/Nb eight-layer film and Mg- 10 at% Nb alloy film exhibit excellent de/hydrogenation properties. Mg- 10 at% Nb alloy film starts to release hydrogen at 108 ℃, and its desorption peak temperature is lower to 146 ℃, which is much better than that of pure MgH2 under the same condi- tion. Scanning electron microscopy （SEM） results demon- strate that the dispersive Nb nanoparticles in Mg/Nb eight- layer film may serve as nucleation sites for Mg ←→ MgH2 reactions, which can provide channels for H diffusion. For Mg- 10 at% Nb alloy film, the uniform distributions of Nb can accelerate the hydrogen diffusion and effectively improve the dehydrogenation kinetics for MgH2. This study provides an enlightening way for designing and preparing Mg-based composite films with excellent dehydrogenation properties.展开更多
A1N/Co nanocomposite thin films were fabricated by pulsed laser deposition and investigated as new anode materials for lithium-ion batteries for the first time. The combination of electrochemically inactive A1N and Co...A1N/Co nanocomposite thin films were fabricated by pulsed laser deposition and investigated as new anode materials for lithium-ion batteries for the first time. The combination of electrochemically inactive A1N and Co in nanometer scale boosted the electrochemical performance of the thin films surprisingly. A high reversible capacity of 555 mAh.g^-1 after 100 discharge-charge cycles at a current density of 500 mA.g^-1 is obtained for the A1N/Co nanocomposite thin films, and 372 mAh.g^-1 can be retained at a high rate up to 16C, exhibiting promising cycle stability and rate capability. The electrochemical reaction mechanism study reveals that Co nanoparticles could not only provide high electronic conductivity for the thin films, which facilitate the thorough decomposition of A1N in the initial discharge process, but also react with Li3N to form a new species CozN during charge process, thus ensuring large capacity and high reversibility of A1N/Co nanocomposite thin films in sub- sequent cycles. This study provides a new perspective to design advanced electrode materials for lithium-ion batteries.展开更多
Large and variable in-plane uniaxial magnetic anisotropy in a nanocrystalline （Co2FeA1）97.8（Al2O3）2.2 soft magnetic thin film is obtained by an oblique sputtering method without being induced by magnetic field or ...Large and variable in-plane uniaxial magnetic anisotropy in a nanocrystalline （Co2FeA1）97.8（Al2O3）2.2 soft magnetic thin film is obtained by an oblique sputtering method without being induced by magnetic field or post anneaiing. The in-plane uniaxiai magnetic anisotropy varies from 50 Oe to 180 Oe （1 Oe=79.5775 A·m-1） by adjusting the sample＇s position. As a result, the ferromagnetic resonance frequency of the film increases from 1.9 GHz to 3.75 GHz.展开更多
An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being cons...An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51621001,51571091,and 51471070)Guangdong Natural Science Foundation(Nos.2016A030312011 and 2014A030313222)
文摘t To investigate the effect of Nb on the dehydro- genation properties of Mg-Nb composite films, Mg/Nb eight- layer film and Mg- 10 at% Nb alloy film with the similar Mg- to-Nb atomic ratio were prepared by magnetron sputtering. Results show that both Mg/Nb eight-layer film and Mg- 10 at% Nb alloy film exhibit excellent de/hydrogenation properties. Mg- 10 at% Nb alloy film starts to release hydrogen at 108 ℃, and its desorption peak temperature is lower to 146 ℃, which is much better than that of pure MgH2 under the same condi- tion. Scanning electron microscopy （SEM） results demon- strate that the dispersive Nb nanoparticles in Mg/Nb eight- layer film may serve as nucleation sites for Mg ←→ MgH2 reactions, which can provide channels for H diffusion. For Mg- 10 at% Nb alloy film, the uniform distributions of Nb can accelerate the hydrogen diffusion and effectively improve the dehydrogenation kinetics for MgH2. This study provides an enlightening way for designing and preparing Mg-based composite films with excellent dehydrogenation properties.
基金financially supported by the National Natural Science Foundation of China (No.51502039)
文摘A1N/Co nanocomposite thin films were fabricated by pulsed laser deposition and investigated as new anode materials for lithium-ion batteries for the first time. The combination of electrochemically inactive A1N and Co in nanometer scale boosted the electrochemical performance of the thin films surprisingly. A high reversible capacity of 555 mAh.g^-1 after 100 discharge-charge cycles at a current density of 500 mA.g^-1 is obtained for the A1N/Co nanocomposite thin films, and 372 mAh.g^-1 can be retained at a high rate up to 16C, exhibiting promising cycle stability and rate capability. The electrochemical reaction mechanism study reveals that Co nanoparticles could not only provide high electronic conductivity for the thin films, which facilitate the thorough decomposition of A1N in the initial discharge process, but also react with Li3N to form a new species CozN during charge process, thus ensuring large capacity and high reversibility of A1N/Co nanocomposite thin films in sub- sequent cycles. This study provides a new perspective to design advanced electrode materials for lithium-ion batteries.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074040)the Key Project of Shandong Provincial Department of Science and Technology,China(Grant No.ZR2012FZ006)the Fujian Provincial Science Foundation for Distinguished Young Scholars,China(Grant No.2010J06001)
文摘Large and variable in-plane uniaxial magnetic anisotropy in a nanocrystalline （Co2FeA1）97.8（Al2O3）2.2 soft magnetic thin film is obtained by an oblique sputtering method without being induced by magnetic field or post anneaiing. The in-plane uniaxiai magnetic anisotropy varies from 50 Oe to 180 Oe （1 Oe=79.5775 A·m-1） by adjusting the sample＇s position. As a result, the ferromagnetic resonance frequency of the film increases from 1.9 GHz to 3.75 GHz.
基金Project supported by National Ministries and Commissions(Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities,China(Grant Nos.72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2010JQ8008)
文摘An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.
