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

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

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

Formation and magnetic properties of Fe-Pt alloy clusters by plasma-gas condensation

Size-monodispersed FexPt1-x alloy clusters were synthesized using a plasma-gas-condensation technique which employs two separate elemental sputtering sources and a growth chamber. The composition of the alloy clusters was controlled by adjusting the ratio of the applied sputtering power. We found that high-temperature disordered fcc-FexPt1-x clusters whose mean diameters of 6-9 nm depend on the Ar gas flow ratio were formed for a wide average composition range (xapproximate to0.3-0.7), and the lattice constant of as-doposited clusters increases almost linearly with decreasing x, being extrapolated to the value of pure Pt metal. For Fe49Pt51 cluster-assembled films, high coercivity (8.8 kOe) was obtained by annealing at 600 degreesC within 10 min due to improved chemical ordering, although as-deposited cluster-assembled films have lower blocking temperatures than room temperature, and show a small coercivity value (similar to25 Oe) at room temperature due to intercluster magnetic interaction. (C) 2003 American Institute of Physics

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

Effects of O-2 gas on the size and structure of Cr clusters formed by plasma-gas-condensation

Cr clusters have been produced by a plasma-gas-condensation type cluster deposition apparatus, and studied using a time-of-flight mass spectrometer and a transmission electron microscope. The Cr clusters formed in high pressure inert (Ar and/or lie) gas atmosphere are of an A15-type structure. When an O-2. Ps is mixed with the inert gases in the source (sputtering) chamber, a bcc phase is formed together with Cr2O3. The O-2 gas introduction leads to an increase in the gas temperature of the source chamber probably due to release of the formation enthalpy of the oxide. The A15 phase is annealed by such excess heat and becomes the equilibrium bee phase. The sizes of bee clusters are smaller than those of the A15-clusters, probably due to the heterogeneous nucleation promoted by the oxide formation

Structure and magnetic properties of FePt alloy cluster-assembled films

We studied structure and magnetic properties of FexPt1-x alloy clusters fabricated by a plasma-gas-condensation technique which employs two separate elemental sputtering sources and a growth chamber. Fe and Pt metal vapors generated were cooled rapidly in an Ar atmosphere, and grown into alloy clusters. Most of the as-deposited FexPt1-x alloy clusters are multiply twinned and have predominantly an icosahedral structure. The experimental results also show that there is a narrow distribution of the chemical composition among individual clusters but the Fe and Pt atoms are distributed homogeneously in as-deposited alloy clusters, which is discussed on the basis of a formation process of the alloy clusters in the inert gas-condensation process. The optimal magnetic hardening or the chemically ordered FCT FePt clusters can be achieved at proper annealing temperature for very short annealing time. (C) 2003 Elsevier B.V. All rights reserved

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