Project Basic research on high efficiency energy storage devices based on nanostructured materials

2016年2月国家科技部组织编制了纳米科技重点专项实施方案并发布了2016年度项目申报指南。通过形式审查、函评、视频答辩等申报环节,纳米科技重点; 专项最终在7个研究方向上启动了43个项目。针对指南中5.2纳米能量存储材料及器件,由厦门大学牵头,联合武汉理工大学、华南理工大学及中山大学,组织; 申报的高效纳米储能材料与器件的基础研究项目获得了支持。本文介绍了高效纳米储能材料与器件的基础研究项目的目的与意义,研究目标,拟解决的关键科学问题; ,研究内容与考核指标,研究团队与研究基础,研究挑战和项目预期效益。Ministry of Science and Technology of the Peoples Republic of China; organizes nano science and technology key implementation project in Feb.; 2016 and releases the annual project declaration Guide. Totally 43; projects focusing on seven different research areas are announced in; Jun. 2016. A research team led by Prof. PENG Dongliang from Xiamen; University with the project title of Basic research on high efficiency; energy storage devices based on nanostructured materials has been; funded. In this project, scientific and technological issues concerning; advanced lithium ion batteries will be studied, aiming to greatly; improve their energy density (3400 W·h/kg) and cycling stability (3500; cycles).国家重点研发计划项

Formation and magnetic properties of the fcc-FeN compound clusters prepared by plasma-gas-condensation

The compound FeN clusters with cluster sizes of d = 8-25 nm were synthesized using a plasma-gas-condensation (PGC) cluster deposition apparatus with changing the nitrogen gas flow rate R-N2, and their crystal structures and magnetic properties were investigated. The fee single-phase FeN clusters which have a tetrahedron shape are obtained, and their lattice parameter is a = 0.428 nm, being close to that (a = 0.433 nm) of ZnS-type FeN films but clearly different from that (a = 0.457 nm) of NaCl-type FeN films. The magnetic measurement results indicate that the present ZnS-type FeN clusters are non-magnetic. The characteristic cusp at T-f = 8 K on the zero field cooling (ZFC) thermomagnetic curve is attributed to superparamagnetic behavior of Fe-oxide layer crystallites formed on the FeN cluster surfaces. (C) 2004 Elsevier B.V. All rights reserved

Shape-selective formation of monodisperse copper nanospheres and nanocubes via disproportionation reaction route and their optical properties

Synthesis of stable and monodisperse Cu nanocrystals of controlled morphology has been a long-standing challenge. In this Article, we report a facile disproportionation reaction approach for the synthesis of such nanocrystals in organic solvents. Either spherical or cubic shapes can be produced, depending on conditions. The typical Cu nanospheres are single crystals with a size of 23.4 ± 1.5 nm, and can self-assemble into three-dimensional (3D) nanocrystal superlattices with a large scale. By manipulating the chemical additives, monodisperse Cu nanocubes with tailorable sizes have also been obtained. The probable formation mechanism of these Cu nanocrystals is discussed. The narrow size distribution results in strong surface plasmon resonance (SPR) peaks even though the resonance is located in the interband transition region. Double SPR peaks are observed in the extinction spectra for the Cu nanocubes with relative large sizes. Theoretical simulation of the extinction spectra indicates that the SPR band located at longer wavelengths is caused by assembly of Cu nanocubes into more complex structures. The synthesis procedure that we report here is expected to foster systematic investigations on the physical properties and self-assembly of Cu nanocrystals with shape and size singularity for their potential applications in photonic and nanoelectronic devices. © 2014 American Chemical Society

Structure and magnetic properties of Co/CoO and Co/Si core-shell cluster assemblies prepared via gas-phase

Plasma-gas condensation cluster deposition systems have been introduced and applied for preparation of Co/CoO and Co/Si clusters assemblies. In Co/CoO cluster assemblies prepared by the single source PGC system with introduction of O-2 gas into the deposition chamber, fee Co cores are covered with NaCl type CoO shells, showing marked enhancement of unidirectional and uniaxial magnetic anisotropy and a clear cross-over phenomenon in the magnetic relaxation from the high temperature thermal regime to the low temperature quantum tunneling regime. In Co/Si cluster assemblies prepared by the double source PGC system, fee Co cores are also covered with amorphous Si rich shells, showing rather small magnetic coercivity. Since Co/CoO and Co/Si core-shell clusters are stable in ambient atmosphere, they will be used as building blocks for novel nano-structure-controlled materials. (c) 2004 Elsevier Ltd. All rights reserved

Electrical resistivity and magnetoresistance in monodispersed oxide-coated Fe cluster assemblies

We systematically studied electrical resistivity and magnetoresistance (MR) of size-monodispersed oxide-coated Fe cluster assemblies with the mean cluster sizes of d = 9-17 nm prepared by a plasma-gas-condensation-type cluster beam deposition system. The electrical resistivity and magnetoresistance strongly depend on the temperature, surface oxidization degree of the clusters (namely O-2 gas flow ratio R-O2), Fe cluster size d, and magnetic field. The oxide-coated Fe cluster assemblies exhibit a large negative MR effect which is further enhanced at low temperatures due to the dominant contribution of the spin-dependent tunneling process between the Fe cores through the oxide shell layers. It has been found that the magnetic field dependence of the MR ratio at all temperatures shows no saturation tendency up to a maximum field H = 50 kOe and completely disagrees with the magnetization curves which indicate a saturation tendency. These results have been interpreted by consideration of the magnetic state of the Fe-oxide shell layers, spin-dependent tunneling mechanism, and intercluster magnetic correlation. The high-field nonsaturation behavior in the magnetoresistance effect is attributed to the spin-disordered structure, which is frozen in a spin-glass-like state at low temperatures, in the surface of the Fe-oxide shell crystallites or the whole thinner Fe-oxide shell layers

Thermomagnetic behaviors of Fe-Cr-N films with perpendicular magnetic anisotropy

The temperature dependence of magnetization has been determined for sputter-deposited Fe-Cr-N films with perpendicular magnetic anisotropy. Decomposition and phase transformation with heating have been determined by X-ray diffraction, differential scanning calorimetry, and thermomagnetometry. There are three magnetic transformation stages in the temperature-rising thermomagnetic curves. The first stage which occurs below 350 degrees C corresponds to the paramagnetic transition of the ferromagnetic alpha-Fe-Cr phase. The second stage (350-550 degrees C) is the decomposition of the alpha-Fe-Cr and nonmagnetic gamma'-(Fe,Cr)(4)N-x phases into the pure alpha-Fe and sigma-FeCr phases, leading to an increase of the magnetization and the disappearance of the perpendicular magnetic anisotropy. The final magnetic transformation stage is the paramagnetic transition (T-c=735 degrees C) of the pure alpha-Fe phase. Since there is no rapid magnetization change between liquid helium temperature and room temperature, the gamma'-(Fe,Cr)(4)N-x phase is nonmagnetic at low temperatures. (C) 1998 Elsevier Science S.A

Electrical properties of oxide-coated metal (Co, Cr, Ti) cluster assemblies

Oxide-coated metal (Co, Cr and Ti) cluster assemblies whose mean cluster sizes are 8-13 nm have been fabricated by a plasma-gas-condensation type cluster beam deposition technique. With increasing oxygen gas flow rate R-O2, the oxide-coated metal cluster-assembled films exhibit a metal-nonmetal transition. In the metallic regime, the resistivity reveals In T dependence at low temperature due to weak localization of conduction electrons and/or electron-electron interactions in the disordered oxide-coated cluster-assembled films. The In T dependence still remains for the very thick oxide-coated metal-cluster-assembled films (the actual thickness t(c) = 2400 nm) which is clearly a three-dimensional system. This behavior can be interpreted by a low dimensionality of the three-dimensional oxide-coated cluster assemblies because of a porous cluster stacking and imperfect or non-uniform oxide shell

Crystal structure of Fe-N clusters prepared by plasma-gas-condensation

Fe-N clusters were prepared by a plasma-gas-condensation cluster deposition apparatus at various nitrogen gas flow rate R-N2, and their crystal structures were investigated by transmission electron microscopy. For R-N2 > 2.2 x 10(-7) mol/s, fcc single-phase FeN clusters are obtained and their lattice parameter is a = 0.428 nm, being close to that (a = 0.433 nm) of ZnS-type FeN films. When R-N2 greater than or equal to 7.5 x 10(-7) mol/s, almost all clusters are of a tetrahedron shape with cluster sizes of d = 8-25 nm. This reveals that the tetrahedron shape of FeN compound clusters is stable in such small sizes, implying a low (111) surface energy and/or high elastic strain energy and twin boundary energy compared with pure metal clusters with fcc structure

Exchange anisotropy of monodispersed Co/CoO cluster assemblies

Monodispersed Co/CoO cluster assemblies with the mean cluster size of 13 nm have been prepared using a plasma-gas-condensation-type cluster beam deposition apparatus. The structural analysis and magnetic measurement indicate that the Co cluster is covered by an oxide shell composed of CoO. The effect of the oxygen gas flow rate during deposition and that of temperature on the coercivity and hysteresis loop shift induced by field cooling were measured. The effect of the CoO shell on the loop shift and the temperature dependence of the exchange anisotropy are discussed. The unidirectional anisotropy is negligible above 200 K for the present assemblies. This is ascribed to the rapid decrease of the anisotropy of the antiferromagnetic interfacial layers near the inter-face of the Co cores and CoO shells

Effect of heat treatment on structure and magnetic properties of the Fe-N and Fe-Ti-N alloy films

Fe-N and Fe-Ti-N alloy films have been prepared by reactive sputtering. The structure and magnetic properties of the Fe-Ti-N and Fe-N films have been studied as a function of the N-2 flow rate R(N-2) and annealing temperature T-A by X-ray diffraction (XRD) and a vibrating sample magnetometer. The as-prepared and annealed Fe-N films consist of the alpha-Fe and Fe4N phases but the Fe-Ti-N films are composed of the alpha-Fe and Ti2N phases. The coercivity, H-c, of the Fe-N films changes drastically with R(N-2) and T-A, while that of the Fe-Ti-N films does not change with T-A up to 500 degrees C. These results indicate that the addition of Ti suppresses the formation of iron nitride phases and improves the thermal stability of Fe-N films. (C) 1997 Elsevier Science S.A