AbstractBoosting power density is one of the primary challenges that current lithium ion batteries face. Alloying anodes that possess suitable potential windows stand at the forefront in pursuing ultrafast and highly reversible lithium storage to achieve high power/energy lithium ion batteries. Herein, ultrafast lithium storage in Sn-based nanocomposite anodes is demonstrated, which is boosted by pseudocapacitance benefitting from a high fraction of highly interconnected interfaces of Fe/Sn/Li2O. By tailoring the voltage window in the range of 0.005–1.2 V for the alloying/dealloying reactions, such Sn-based nanocomposite anodes achieve simultaneous ultrahigh rate capability, superlong cycling performance, and close-to-100% Coulombic efficiency. The nanocomposite anode delivers a high reversible capacity (≈420 mAh g−1) at 1 A g−1 for more than 1200 cycles, corresponding to only 0.016% per cycle of capacity decay. A reversible capacity of 350 mAh g−1 can be maintained at an ultrahigh current density of 80 A g−1, with 67.3% capacity retention relative to the capacity at 1 A g−1. This combination of pseudocapacitive lithium storage and spatially confined electrochemical reactions in Sn-based nanocomposite anode materials may pave the way for the development of high power/energy and long life lithium ion batteries.

AbstractThe realization of high-power lithium-ion batteries (LIBs) is heavily hampered by intrinsically slow lithium diffusion within solid electrodes. Capacitive-like lithium storage behavior observed in transition-metal oxide (TMO)-based anodes shed light on attaining battery-like capacity and supercapacitor-like rate performance simultaneously. Herein, “honeycomb”-like Mn2O3 films were successfully demonstrated as anodes for LIBs, in which the pseudocapacitive effect is strengthened upon cycling, resulting in a high-rate lithium storage capability. Such pseudocapacitance originates from the unique porous structure and cycle-induced microstructure evolution. The reticular Mn2O3 can reach 1584.9 mAh g−1 over 250 cycles at 1 A g−1, 1564.9 mAh g−1 after 500 cycles at 5 A −1, and 475.6 mAh g−1 at 15 A g−1.

•Coercivity of Nd-Ce-Fe-B sintered magnets can be effectively enhanced by grain boundary restructuring with (Nd, Pr)-H.•Formation of (Nd,Pr)-rich shell surrounding Ce-rich grain core strengthens the local magnetocrystalline anisotropy.•Formation of smooth and continuous grain boundaries promotes the magnetic isolation between adjacent grains.•The obtained Nd-Ce-Fe-B magnets have much lower cost than the commercial ones with comparable magnetic properties.Incorporating the highly abundant rare earth (RE) Ce into Nd-Fe-B sintered magnets has attracted considerable interest recently. The inferior anisotropic field (HA) of Ce2Fe14B to Nd2Fe14B, however leads to low coercivity of the Nd-Ce-Fe-B magnets. To further enhance the coercivity, in this work, (Nd, Pr)-H powders were used as intergranular additive to restructure the grain boundaries of the low cost (Nd,Pr)22.3Ce8.24FebalB1 (wt.%) sintered magnets. When added with only 2 wt% (Nd, Pr)-H, the Hcj can be enhanced from 10.6 kOe to 12.7 kOe with slight reduction in remanence and maximum energy product. The dehydrogenation of (Nd, Pr)-H during sintering promotes the diffusion of Nd and Pr towards the 2:14:1 phase grains and the smoothing of grain boundaries. The formation of (Nd, Pr)-rich shell with locally enhanced magnetocrystalline anisotropy and the magnetic isolation between adjacent 2:14:1 phase grains result in obvious coercivity enhancement, which was supported by magnetic domain structure characterizations and micromagnetic simulations. It suggests that through grain boundary restructuring, the coercivity of Nd-Ce-Fe-B magnets can be enhanced to be comparable of commercial Nd-Fe-B magnets, which may shed new insights into the fabrication of low cost RE permanent magnets.Download high-res image (403KB)Download full-size image

•Activated carbon confined LiBH4 doped with CeF3 was prepared.•LiBH4-AC-CeF3 starts to release hydrogen at around 160 °C.•The maximum hydrogen release speed of LiBH4-AC-CeF3 is 288 times higher than that of LiBH4 at 350 °C.•LiBH4-AC-CeF3 shows reversible hydrogen storage capacity of 9.3 wt%.CeF3 as a catalyst is first added to activated carbon (AC) by ball milling under low rotation speed. Then the treated AC was used as the scaffold to confine LiBH4 by melt infiltration process. The combined effects of confinement and CeF3 doping on the hydrogen storage properties of LiBH4 are studied. The experimental results show that LiBH4 and CeF3 are well dispersed in the AC scaffold and occupy up to 90% of the pores of AC. Compared with pristine LiBH4, the onset dehydrogenation temperature for LiBH4-AC and LiBH4-AC-CeF3 decreases by 150 and 190 °C, respectively. And the corresponding dehydrogenation capacity increases from 8.2 wt% to 13.1 wt% for LiBH4-AC and 12.8 wt% for LiBH4-AC-CeF3, respectively. The maximum dehydrogenation speed of LiBH4-AC and LiBH4-AC-CeF3 is 80 and 288 times higher than that of pristine LiBH4 at 350 °C. And LiBH4-AC andLiBH4-AC-CeF3 show good reversible hydrogen storage properties. On the during 4th dehydrogenation cycle, the hydrogen release capacity of LiBH4-AC and LiBH4-AC-5 wt% CeF3 reaches 8.1 and 9.3 wt%, respectively.

•Nanocomposite Nd7Y6Fe61B22Mo4 sheet magnets were synthesized by injection casting.•High coercivity of 1289 kA/m was obtained for the directly casted magnet.•Magnetic properties arise from magnetically exchange coupled soft and hard phases.The phase composition, magnetic and microstructural properties of Nd2Fe14B/(α-Fe, Fe3B) nanocomposite magnets produced by injection casting technique have been studied. Magnetic hysteresis loop of the Nd7Y6Fe61B22Mo4 permanent magnet demonstrates the coercivity as high as 1289 kA/m. Electron microscopy elucidates a microstructure composed of magnetically soft α-Fe, Fe3B and hard Nd2Fe14B/Y2Fe14B nanograins (20–50 nm) separated by ultra-thin grain boundary layer. The Henkel plot curve of the Nd7Y6Fe61B22Mo4 magnet yields the existence of exchange coupling interactions between soft and hard phases. Macroscopically large size sheet magnet is obtained due to high glass forming ability of the Nd7Y6Fe61B22Mo4 alloy derived from large atomic radius mismatch and negative enthalpy of alloy constituent elements. The high coercivity of the magnet is attributed to the magnetically hard phase increment, nucleation of reverse domains and the presence of thin grain boundary phase. Good magnetic properties such as remanence of 0.51 T, coercivity of 1289 kA/m and maximum energy product of 46.2 kJ/m3 are obtained in directly casted Nd7Y6Fe61B22Mo4 sheet magnets.

•Alkaline bluing as a new method to fabricate insulation coatings surrounding magnetic powders.•Effects of reaction time on the magnetic performance of the SMCs investigated.•Growth mechanism of the coatings revealed based on which the oxidation process has been improved.•Ferromagnetic Fe3O4 coating achieved for improved magnetic properties of the SMCs.Soft magnetic composites (SMCs) containing Fe powders embedded in insulating matrix have been fabricated via alkaline bluing as a new method. Effects of reaction time on the magnetic properties of the SMCs have been investigated. Mechanism of the oxidation process has also been revealed, which involves initial oxidation of Fe into Fe2+ (Na2FeO2) and Fe3+ (Na2Fe2O4) by NaNO2 and NaNO3 followed by hydrolysis of Fe2+ and Fe3+ into Fe3O4. Hydrolysis of the excessive Fe3+ leads to the formation of Fe2O3 which reduced the effective permeability of the SMCs. To form pure Fe3O4 coating, the reaction process has been improved to suppress the Fe3+ hydrolysis. The obtained ferromagnetic Fe3O4 coating effectively reduces magnetic dilution, while its high electrical resistivity allows satisfactory insulation between the Fe powders, giving rise to simultaneous high effective permeability (97.7) and low core loss (771.3 mW/cm3) of the SMC.

•Resorcinol formaldehyde carbon aerogel (RFC) was synthesized as a scaffold.•LiBH4 and LiAlH4 were nanoconfined into RFC by a two-step melt-infiltration process.•2LiBH4-LiAlH4/RFC shows good hydrogen storage properties.•A reversible hydrogen storage capacity of 5.7 wt.% is achieved.Resorcinol formaldehyde carbon aerogel (RFC)was synthesized in this paper to be used as a scaffold for nanoconfining 2LiBH4-LiAlH4composite. LiBH4 and LiAlH4 were nanoconfined into the pores of the prepared resorcinol formaldehyde carbon aerogel by a two-step melt-infiltration process. The microstructure evolution was investigated by XRD, FTIR analysis, and BET measurements. The hydrogen storage properties were studied by TPD, TG/DSC/MS measurements. The experimental results show that LiBH4 and LiAlH4 are well dispersed in the scaffold after the melt infiltration process. The nano-confined 2LiBH4-LiAlH4 composite (denoted as 2LiBH4-LiAlH4/RFC) shows a two-step dehydrogenation process. The onset dehydrogenation temperatures for the two steps are 100 °C and 280 °C, respectively, which are 70 °C and 170 °C lower than that of the milled 2LiBH4-LiAlH4 mixture. The formation of AlB2 during the second dehydrogenation step alters the reaction pathway of LiBH4. The kinetic properties of the composite are greatly enhanced compared to the physical mixture of LiBH4 and LiAlH4. The nanoconfinement and the formation of AlB2 have a combined effect on the improvement of hydrogen storage properties for nanoconfined 2LiBH4-LiAlH4/RFC. It could be rehydrogenated at 350 °C and 5 MPa H2. A reversible hydrogen storage capacity of 5.7 wt.% is achieved.

软磁复合材料是软磁金属经制粉、绝缘处理、粘 结、压制和热处理而制备的磁性复合材料, 广泛 应用于能源、信息、交通和国防等重要领域, 是 国民经济和国防建设的关键基础材料。随着电力 和电子装备向高频、高功率密度、节能和电磁兼 容方向发展, 软磁复合材料的需求量越来越大, 要求也越来越高。我国软磁复合材料过去长期存 在功率损耗大、磁通密度低、直流叠加性能差等 严重问题, 技术水平与国外差距巨大。2002 年以 来, 浙江大学严密教授团队与相关企业进行了长 期的合作研究, 原创性提出了制备多软磁相核壳 结构复合材料的技术思路, 创新了绝缘包覆技 术, 大幅消除了颗粒间涡流损耗; 建立了软磁合 金新体系, 显著提高了复合材料软磁性能; 创新 和集成核心生产技术, 实现了规模化生产和广泛 的实际应用。1. 发明多软磁相核壳结构复合材料和磁粉绝缘 包覆新技术。降低以涡流损耗为主的功率损耗, 是软磁复合材料的世界性难题。本项目提出了在 软磁粉末基体上原位生成高电阻率软磁壳层, 制 备多软磁相核壳结构复合材料以降低涡流损耗 的新思路, 发明了Fe 基软磁合金基体与 Fe4N/Fe3O4、Fe3O4 等高电阻率软磁壳层组成的核 壳结构材料。创新了磁粉绝缘包覆技术, 发明了分别适用于不同合金磁粉的非均匀形核、溶胶- 凝胶和复合绝缘包覆技术。以上发明在保持高磁 性能的同时, 大幅度抑制了颗粒间涡流, 显著降 低了功率损耗。2. 发明系列新型高性能软磁合 金。创新设计了Fe-Si-M、Fe-Ni-M(M为Mo、 Ni、Al 或Co)新型晶态软磁合金和Fe-Cu-Nb- Ti-Si-B、Fe-Ni-Al-Si-B 纳米晶/非晶软磁新合金, 掌握了成分配方对合金相结构、显微组织和磁性 能的作用规律及机理, 发明了系列新型高性能软 磁合金, 制备出具有高磁通密度、高直流叠加等 不同特性的高性能软磁复合材料产品。3. 创新和 集成核心生产与应用技术。发明了新型耐高温粘 结剂和有机-无机复合粘结技术, 创新和改进了针对不同合金的磁粉制备技术, 系统集成相关发明 与关键技术, 建立了低功耗高性能软磁复合材料 成套生产工艺。项目创新成果已在合作企业全面应用, 为新能源 汽车、高铁、计算机及国防领域做出了重要贡献, 并获得了2016 年度国家技术发明奖二等奖。值 得一提的是, 这已是严密教授团队获得的第二个 国家技术发明奖二等奖。2013 年度, 严密教授团 队完成的“钕铁硼晶界组织重构及低成本高性能 磁体生产关键技术”项目亦获得国家技术发明奖 二等奖。

•A novel LiAlBH composite is prepared by ball milling LiBH4 and AlH3.•LiBH4AlH3 shows better hydrogen desorption property than LiBH4Al.•Reaction mechanism between LiBH4 and AlH3 is revealed.•Desorption products of 2LiBH4AlH3 are AlB2 and LiAlB compounds.•Product yield depends on the free surface area of Al particle.Lithium borohydride (LiBH4) possesses a very high hydrogen capacity (18.5 wt%) but suffers from high thermal stability. In this work, the as-prepared aluminium hydride (AlH3) was ball milled with LiBH4 forming 2LiBH4 + AlH3 composite to improve the hydrogen desorption properties of LiBH4. Hydrogen desorption measurements showed that a hydrogen capacity of 11.2 wt% is obtained from the 2LiBH4 + AlH3 composite and the desorption temperature of LiBH4 with AlH3 addition is reduced by more than 30 °C. AlH3 is better as an Al source than the as-received Al in that the hydrogen desorption extent of AlH3-doped LiBH4 reaches 70%, while it is 54% and 61% for the pure LiBH4 and the Al-doped LiBH4. This is due to the brittle and oxide-free nature of AlH3. Microstructure investigations showed that during heating process, the 2LiBH4 + AlH3 composite undergoes AlH3 decomposition forming Al* and releasing hydrogen, followed by the decomposition of LiBH4. LiBH4 will react with Al* forming AlB2 and LiAlB compounds during its decomposition, which contributes to the improved hydrogen desorption properties of LiBH4.Hydrogen desorption behaviours of the LiBH4AlH3 composite.

•Thermal oxidation as a new method to fabricate insulation coating for SMCs.•Sole ferromagnetic Fe3O4 achieved as the inorganic coating for excellent magnetic performance.•Evolution of the insulation matrix during annealing investigated.•Annealing effects on the properties of SMCs revealed and correlated to the matrix evolution.Fe soft magnetic composites (SMCs) containing Fe powders embedded in Fe3O4/epoxy-modified silicone resin (ESR) matrix have been fabricated via thermal oxidation of Fe powders with H2O under alkalic conditions, prior to mixing with ESR. The ferromagnetic Fe3O4 coating effectively reduces magnetic dilution, while high electrical resistivity of both Fe3O4 and ESR provides satisfactory insulation of the SMCs, giving rise to simultaneous high permeability and low core loss. Evolution of the Fe3O4/ESR matrix during the annealing process has been investigated, which is correlated to changes in the magnetic properties of the SMCs. The ESR starts to decompose at around 382 °C, leaving reducing groups which then convert the Fe3O4 coating into Fe with increased annealing temperature to 466 °C. Further raised annealing temperature to 570 °C leads to the reduction of Fe3O4 into FeO. Such evolution provides in-sight information on choosing appropriate annealing conditions to avoid decomposition of the Fe3O4/ESR matrix and can be expanded to other Fe-based SMCs.

•Nanocrystalline phase formation and stress relaxation achieved by annealing the FeCuNbSiB SMCs.•Crystallization initiates with increased nucleation sites followed by existing crystal growth and coalescence.•Stress relaxation completes with increased annealing temperature.•Excellent magnetic performance obtained by coupling of nanocrystals and minimized anisotropy.Fe73.5Cu1Nb3Si15.5B7 amorphous alloy was fabricated into nanocrystalline soft magnetic composites (SMCs). Crystallization process and the evolution of stress relaxation of the SMCs during annealing have been investigated and their effects on the magnetic properties are revealed. Crystallization of the amorphous alloy is accomplished by increment of nucleation sites with the annealing temperature ranged from 500 °C to 600 °C. Stress induced by milling and compaction relieves with increased annealing temperature and complete relaxation can be achieved at around 575 °C. Coupling of small grains (9.1 nm–12.8 nm) and stress relaxation ensures the FeCuNbSiB SMCs of relatively low coercivity, high permeability and low loss. Further raised annealing temperature above 600 °C leads to dominating growth and coalescence of the existing α-Fe(Si) grains and the precipitation of the Fe23B6 phase, which deteriorates the magnetic properties. Optimized soft magnetic properties of the SMCs such as small coercivity (4.5 Oe), large effective permeability (115) and low total core loss (200 mW/cm3 measured when Bm = 0.1 T and f = 50 kHz) can be achieved by post-annealing at 575 °C.

Spatially-confined electrochemical reactions are firstly realized in a highly dense nanocomposite anode for high performance lithium ion batteries. The spatially-confined lithiation–delithiation effectively avoids inter-cluster migration and perfectly retains full structural integrity. Large reversible capacity, high rate capability and superior cycling stability are achieved simultaneously. This spatially-confined lithiation–delithiation offers novel insight to enhance cycling performance of high capacity anode materials.

The compound Tm5Ge4 is the last one in the family of R5Ge4 (R = rare earth elements with magnetic moments) compounds (exclusive of Pm and Eu) whose magnetic properties are still unknown. We prepared high quality Tm5Ge4, and report the detailed crystal structure and magnetic properties. Tm5Ge4 crystallizes in the Sm5Ge4-type orthorhombic structure at room temperature, and orders antiferromagnetically at = 13 and TN = 21 K. The paramagnetic Curie temperature of Tm5Ge4 is positive (θp = 16 K), and the effective magnetic moment (peff = 7.4 μB/Tm) is in good agreement with the theoretical value of 7.56 μB/Tm3+. The ac susceptibility of Tm5Ge4 shows obvious frequency dependence behaviors suggesting the existence of a ferromagnetic cluster in the antiferromagnetic substance. According to the magnetic hysteresis loop, the intrinsic coercivity of Tm5Ge4 is 2616 Oe at 2 K. Tm5Ge4 exhibits an oscillating magnetocaloric effect owing to a metamagnetic-like transformation induced by a critical magnetic field below 21 K.

•A series of Co3O4/KB composites cathodes in lithium oxygen batteries were prepared.•Co3O4/KB (80%) shows largest capacity, lowest overpotential and best stability.•The relationship of electrical conductivity and catalytic activity is studied.A series of Co3O4/Ketjen Black cathodes are fabricated by electrostatic spray deposition technique for Li–O2 batteries. A sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction processes is noted either when Co3O4 is lacked or Ketjen Black is insufficient, which leads to much higher overpotentials between charge and discharge profiles. By contrast, with the optimal design in terms of electric conduction and catalytic activity, the Co3O4/Ketjen Black (80 wt%) composite achieves enhanced electrochemical performance with an initial discharge capacity of 2044 mAh g−1 and maintaining 33 cycles at a fixed capacity of 500 mAh g−1. The electrochemical characterization indicates that the improved Li–O2 battery performance may benefit from the highest oxygen reduction reaction and oxygen evolution reaction activity under this electro-chemically optimized composite. This work may shed light on the design principle of future cathode materials for Li–O2 batteries.

•The nonstoichiometric Er1−xCo2 compounds are identified.•Er atomic vacancies lead to the volume contracting by 0.37% and enhance TC by 44%.•The anomalous susceptibility behavior is not exact the same with the Griffiths phase.•The refrigerant capacity of Er0.97Co2 increases from 152 J/kg to 158 J/kg.ErCo2 compound is a well-known magnetocaloric material which shows giant magnetocaloric effect in the vicinity of first-order phase transition. We demonstrate a new way of fine tuning its crystal structure and magnetic properties. Er atomic vacancies are introduced in order to manipulate the local atomic environment, the phase transition characteristics, and the magnetocaloric effect as well. Er1−xCo2 can be stable over a narrow homogenous range, and maintain the cubic structure. The Bragg peaks shift upward to higher angles, and the unit cell volume contracts with reduction of the Er content. The Curie temperatures in low magnetic field increase from 32 K (ErCo2) to 46 K (Er0.97Co2), and linearly change with the magnetic field in nearly same slope. Er1−xCo2 compounds exhibit anomalous susceptibility behaviors in the paramagnetic state, and deviate from the Curie–Weiss law at around 100 K. The temperature range of anomalous susceptibility behaviors also move upward to higher temperature with reduction of Er content. Er1−xCo2 compounds also show anomalous coercivity behavior in the vicinity of phase transition. Er1−xCo2 compounds exhibit large magnetocaloric effect and good refrigerant capacity in the vicinity of ferrimagnetic–paramagnetic phase transition.

Metal Al was ball milled with CaH2 to improve its hydrolysis properties. The effects of reaction temperature and milling conditions on the hydrogen generation performances of Al are investigated. A higher temperature has been shown to be beneficial for the hydrolysis of Al–CaH2 composites. With increasing the added amount of CaH2 and milling time, the grain size of Al is decreased and the protective oxide film on the surface of the Al powder is damaged. The hydrolysis of CaH2 helps to open up the structure of Al grains and provide OH− to enhance the corrosion of Al. As a result, the hydrogen production of Al powder has been greatly optimized, and the addition of CaH2 proves to be more effective than the addition of some other hydrides. The yield and maximum hydrogen generation rate (mHGR) of an Al-10 mol% CaH2 mixture milled for 15 h are 97.8% and 2074.3 mL min−1 g−1, respectively.

•Two-powder magnet provided a method to increase corrosion resistance of NdFeB.•Increased corrosion resistance relates to occurrence of (Pr,Nd)6Fe13Cu.•(Pr,Nd)6Fe13Cu phase improves chemical stability of anodic intergranular phases.•(Pr,Nd)6Fe13Cu inhibits formation of active reaction channels in grain boundaries.Aiming to improve the corrosion resistance without sacrificing magnetic properties, two-powder magnets were fabricated by additions of (Pr, Nd)32.5Fe62.0Cu5.5 aid alloys to (Pr, Nd)12.6Fe81.3B6.1 master alloys. It was found that these two-powder magnets have similarly comprehensive magnetic properties and even the magnet with 12 wt% additives possesses better magnetic/anticorrosion properties than contrastive one-powder magnets of (Pr, Nd)14.5Fe79.5B6.0 and (Pr, Nd)14.5Fe79.5Cu0.5B5.5. Higher corrosion resistance of the two-powder magnets are related to the replacement of (Pr, Nd)-rich intergranular phase by (Pr, Nd)6Fe13Cu. It is due to the higher corrosion stability of (Pr, Nd)6Fe13Cu, which inhibits the formation of active reaction channels, thus decreasing the corrosion current density and improving the corrosion resistance.

Alumina has been prepared by sol–gel method as the coating layer in the fabrication of FeSiAl soft magnetic composites (SMCs). Influence of the Al2O3 content on the magnetic properties of the SMCs has been studied, and optimized effective permeability (μe = 116.3) and core loss (Pcv = 331.2 mW cm−3) measured at 50 kHz, 100 mT was achieved with 0.8 wt% Al2O3. Hybrid phosphate-alumina coating has also been used to prepare the FeSiAl SMCs with a total addition of 0.8 wt%. Significantly improved performance of the SMCs can be achieved with the hybrid coating compared to single phosphate or alumina coating. The addition of 0.2 wt% H3PO4 and 0.6 wt% Al2O3 gives rise to the optimal magnetic properties (μe = 123.4; Pcv = 226.4 mW cm−3) of the FeSiAl SMCs. For the hybrid coating, the inner phosphate layer grown by direction reaction at the powder surfaces gives rise to excellent adhesion. Also, investigation on the thermal stability of the coatings indicates that the outer Al2O3 layer hinders the decomposition of the phosphate layer, leading to enhanced magnetic performance of the SMCs.

Sodium ion batteries are attracting ever-increasing attention for the applications in large/grid scale energy storage systems. However, the research on novel Na-storage electrode materials is still in its infancy, and the cycling stability, specific capacity, and rate capability of the reported electrode materials cannot satisfy the demands of practical applications. Herein, a high performance Sb2O3 anode electrochemically reacted via the reversible conversion-alloying mechanism is demonstrated for the first time. The Sb2O3 anode exhibits a high capacity of 550 mAh g–1 at 0.05 A g–1 and 265 mAh g–1 at 5 A g–1. A reversible capacity of 414 mAh g–1 at 0.5 A g–1 is achieved after 200 stable cycles. The synergistic effect involving conversion and alloying reactions promotes stabilizing the structure of the active material and accelerating the kinetics of the reaction. The mechanism may offer a well-balanced approach for sodium storage to create high capacity and cycle-stable anode materials.Keywords: alloying; anode; conversion; Sb2O3; sodium ion battery

•Novel effects of LiBH4 and NiCl2 on hydrolysis of Mg have been studied.•A synergistic effect between Mg and LiBH4 has been found primarily.•Milling time and sample composition are vital factors affecting the hydrolysis.•Effects of in situ deposition of Ni on the hydrolysis have been investigated.A novel method to promote the Mg–H2O hydrolysis reaction is proposed. Among the hydrides tested, LiBH4 offers the best performance. By ball-milling Mg powder with LiBH4, the maximum hydrogen generation rate (mHGR) and yield are significantly increased. More importantly, the hydrolysis properties are further improved when NiCl2 is added. The newly formed Mg–LiBH4–NiCl2 system reaches an mHGR of 1655 ml min−1 g−1 and yield of 96.1%. The factors influencing the hydrogen generation performance of this system, such as sample composition and milling time, are investigated. Different methods of characterization, such as X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy are used for the preliminary mechanistic study. The milling conditions and the in situ deposition of metallic Ni are both believed to be important factors that benefit the overall hydrolysis process.

•Cu and Nb powders were co-added as intergranular modifiers to improve corrosion resistance of NdFeB magnets.•Corrosion resistance is significantly improved; Mass loss by PCT test reduces 80%.•High magnetic properties are retained, with Br = 13.6 kGs, Hcj = 11.4 kOe, and (BH)max = 46.2 MGOe.Cu and Nb powders are co-added as intergranular modifiers to improve the corrosion resistance of Nd–Fe–B sintered magnets. For the magnet co-added with 0.2 wt.% Cu and 0.8 wt.% Nb, mass loss of accelerated corrosion test in 120 °C, 2 bar and 100% relative humid atmosphere for 96 h drops from 2.47 mg/cm2 to 0.49 mg/cm2 in comparison with the Cu/Nb free one. The corrosion potential Ecorr in 3.5% NaCl aqueous solution increases from −1.115 V to −0.799 V, which indicates the better resistance against electrochemical corrosion. The improved corrosion resistance is ascribed to the enhanced stability of the intergranular phase by forming high electrode potential Cu-containing phase and reduced Nd-rich phase at triple junctions. Besides, the distribution of (Pr, Nd)-rich phases along the grain boundaries becomes more clear and continuous through Cu/Nb co-addition, maintaining fairly good magnetic properties of Br = 13.6 kGs, Hcj = 11.4 kOe, (BH)max = 46.2 MGOe. Further investigation demonstrates that Nb is effective to refine the grains of hard magnetic Nd2Fe14B phase and Cu is beneficial for optimizing the distribution of the intergranular phases.

Niobium fluoride (NbF5) is introduced into the MgH2 + 1/4AlH3 hydride composite by ball milling to improve the hydrogen desorption properties of the Mg–Al–H system. It is found that after being ball milled with 1 mol % of NbF5, AlH3 in the composite has almost fully decomposed and forms metallic Al, which indicates that NbF5 can significantly destabilize AlH3. DSC results show that NbF5 addition also helps reduce the peak desorption temperature of MgH2 in the composite from 324 to 280 °C. Isothermal desorption measurements demonstrate that MgH2 in the doped composite can rapidly release 98% of its hydrogen after desorption at 300 °C for 1 h, while the valued is only 46% for the undoped composite. The activation energy for hydrogen desorption of MgH2 in the doped composite is calculated to be 104.5 kJ/mol, much lower than that in the undoped composite (127.4 kJ/mol). These results suggest that NbF5 addition dramatically improves the hydrogen desorption kinetics of the MgH2 + 1/4AlH3 composite. Dehydrogenation–hydrogenation measurements reveal that the hydrogen desorption kinetics of the undoped composite declines with cycle number, whereas the NbF5-doped composite maintains good cycling stability. Microstructure studies indicate that the decline of the kinetics is attributed to the grain growth and particle agglomeration of MgH2 during hydrogen sorption cycling. However, NbF5 addition can suppress this grain growth through the formation of Nb/NbH layers surrounding the particles of MgH2 and acting both as the impediment to grain growth of Mg/MgH2 and as the gateway for hydrogen diffusion. Finally, the role that AlH3 plays in the hydrogen desorption process of the Mg–Al–H composites is discussed.

•A high-performance amorphous Fe2O3 anode is developed for lithium ion batteries.•Amorphization of TMOs may offer a new perspective for high performance LIB anodes.•A capacity of ~1600 mA h g−1 is sustained after 500 cycles at 1 A g−1.•A specific capacity of ~460 mA h g−1 is achieved using an ultra-large 20 A g−1.Despite their widespread application state-of-the-art lithium batteries are still highly limited in terms of capacity, lifetime and safety upon high charging rate. The development of advanced Li-ion batteries with high energy/power density relies increasingly on transition metal oxides. Their conversion reactions enable a combined high capacity and enhanced safety. Nevertheless, their practical application is severely limited by the insufficient cycling stability, poor rate capability and large voltage hysteresis which impact the lifetime and the performance of the battery. Here we report the exceptionally high-performance of an amorphous Fe2O3 anode, which largely outperforms its crystalline counterpart. Besides the advantageous narrow voltage hysteresis, this material exhibits a new breakthrough in terms of cycling stability and rate capacity. A highly reversible charge–discharge capacity of ~1600 mA h g−1 was observed after 500 cycles using a current density of 1000 mA g−1. A specific capacity of ~460 mA h g−1 was achieved using the ever reported large current density of 20,000 mA g−1 (~20 C), which opens venues for high power applications. The amorphous nature of Fe2O3 anode yields a unique electrochemical behavior and enhanced capacitive storage, which drives the overall electrochemical performance. This work demonstrates that amorphous transition metal oxides (a-TMO) based materials may offer a new perspective towards the development of high performing anodes for the next-generation of Li-ion batteries.

•A series of transition metal oxides is successfully demonstrated as anodes for sodium ion batteries.•The sodium uptake/extract is confirmed in the way of reversible conversion reaction.•The pseudocapacitance-type behavior is observed in the contribution of sodium capacity.•For Fe2O3 anode, a reversible capacity of 386 mAh g−1 at 100 mA g−1 is achieved over 200 cycles.•As high as 233 mAh g−1 is sustained even cycling at a large current–density of 5 A g−1.Sodium-ion batteries (SIBs) are attracting considerable attention with expectation of replacing lithium-ion batteries (LIBs) in large-scale energy storage systems (ESSs). To explore high performance anode materials for SIBs is highly desired subject to the current anode research mainly limited to carbonaceous materials. In this study, a series of transition metal oxides (TMOs) is successfully demonstrated as anodes for SIBs for the first time. The sodium uptake/extract is confirmed in the way of reversible conversion reaction. The pseudocapacitance-type behavior is also observed in the contribution of sodium capacity. For Fe2O3 anode, a reversible capacity of 386 mAh g−1at 100 mA g−1 is achieved over 200 cycles; as high as 233 mAh g−1is sustained even cycling at a large current–density of 5 A g−1.

Organometallically prepared AlH3 and as-received Al powders were mixed with MgH2 to improve the dehydriding and rehydriding properties of MgH2. Thermal analysis shows that the onset dehydriding temperature of MgH2 is reduced by 55 °C (or 25 °C) when mixed with AlH3 (or Al). The destabilization of MgH2 is attributed to the formation of Mg–Al alloys through the reaction between MgH2 and Al. Isothermal dehydriding measurements demonstrate that AlH3 and Al both improve the dehydriding kinetic of MgH2 to some extent, and it only takes 44 min for MgH2 + AlH3 (5.4 h for MgH2 + Al) to release 60% of the hydrogen of MgH2 at 300 °C, but 8.6 h are required for as-milled MgH2. The apparent activation energy for the dehydriding of MgH2 is reduced from 174.6 kJ mol−1 for as-milled MgH2 to 154.8 and 138.1 kJ mol−1 for MgH2 mixed with Al and AlH3 respectively; this is responsible for the improvement in the dehydriding kinetics of MgH2. Despite this, AlH3 is better in destabilizing MgH2 than the as-received Al for the fact that Al* formed in situ from the decomposition of AlH3 is oxide-free on the particle surfaces, which effectively increases the chemical activity of Al*. Furthermore, the brittleness of AlH3 makes it easier to mix MgH2 with AlH3, which would result in uniform distributions of Mg and Al and shortening of the diffusion length. Concerning the reversibility, at 300 °C and 5 MPa H2 and MgH2 are fully recovered in the dehydrided MgH2 + Al, and MgH2 + AlH3 samples after rehydriding for 10 h. The rehydriding kinetic of MgH2 is significantly enhanced for the dehydrided MgH2 + AlH3, but not in the case of the MgH2 + Al.

AlH3 is a promising hydrogen storage material due to its high hydrogen capacity (10 wt%) and relatively low dehydriding temperature. In this work, γ-AlH3 was prepared by organometallic synthesis method and the effects of ball milling on dehydriding properties of γ-AlH3 were investigated systematically. Experimental results shows that as-prepared γ-AlH3 releases about 8.3 wt% of hydrogen in the temperature range of 130–160 °C at a heating rate of 2 °C/min. Ball milling significantly improves the dehydriding behavior of γ-AlH3. DSC-MS analysis reveals that the dehydriding temperature of γ-AlH3 ball-milled for 10 h decreases by around 30 °C. In addition, the dehydriding activation energy of γ-AlH3 ball-milled for 2 h decreased from 87 to 68 kJ/mol. Isothermal dehydriding measurements demonstrate that duration needed to release 90% hydrogen for as-prepared γ-AlH3 is 280 min, but it takes only 82 min after ball milled for 10 h to release the same amount of hydrogen. Moreover, the dehydriding path of γ-AlH3 is changed by ball milling. As-prepared γ-AlH3 transforms to α-AlH3 before dehydriding, while ball-milled γ-AlH3 prefers to dehydride directly without firstly transforming to α-AlH3.Highlights► γ-AlH3 was prepared by organometallic synthesis method. ► Dehydriding properties of γ-AlH3 were investigated systematically. ► Ball milling greatly improves the dehydriding behavior of γ-AlH3. ► The dehydriding mechanism was discussed.

We report a tailored synthesis of tin oxide–graphene nanocomposites with variety in oxide phase structure and composition through the control of oxidation–reduction hydrothermal reaction between graphene oxide and Sn2+. The amount ratio of graphene oxide to SnCl2 is critical to achieve either SnO/SnO2–graphene or pure SnO2–graphene composites, which are electrochemically evaluated as the anode materials in lithium ion batteries. It is found that the phase structure and composition play a key role in the lithium ion storage ability. A superior cycling performance is obtained when the nanocomposites exist in pure SnO2–graphene (mass percentage of SnO2: 68%) after 90 cycles, with a reversible capacity of 525 mA h g−1 and an ultra-low capacity loss of ∼0.3% per cycle.Highlights► Phase-tailored hydrothermal synthesis of tin oxide-graphene nanocomposites was realized. ► Schematic illustration was proposed considering the amount ratio of GO to Sn2+. ► Reversible capacity of 525 mA h g−1, and an ultra-low capacity loss of ∼0.3% per cycle after 90 cycles.

Microstructure and crystallographic texture evolution of lean duplex stainless steel 2101 (LDX 2101) during single- and multi-pass hot compressions were studied by electron backscatter diffraction (EBSD). The flow curve characteristics of LDX 2101 were interpreted by coupling behaviors of the microstructure evolution in austenitic and ferric phases. The softening of both the phases during straining is caused by continuous dynamic recrystallization by the gradual transformation of low-angle grain boundaries into high-angle grain boundaries, without obvious changes in the phase ratio. The hot compression textures of the constituent phases show that the brass-type texture, which is typical of face-centered cubic materials with low stacking fault energy, is developed in the austenitic phase, and the rotated-cube texture is developed in the ferric phase. The differences in the microstructures and texture evolution features under different hot deformation modes can be explained by the differences in softening mechanisms.

Electrical transport behaviors of SnO2-based oxides are absolutely essential, either for the understanding of physiochemical properties, or their practical applications. In this paper, an abnormal change in electrical transport is reported upon cobalt doping. A far-from-equilibrium technique—pulsed spray evaporation chemical vapor deposition (PSE-CVD), is investigated for the fabrication of Sn1−xCoxO2−δ (x = 0–0.18) thin films. Upon cobalt doping, the Hall mobility improves gradually and a ten-fold enhancement was noticed for Sn0.82Co0.18O2−δ relative to pure SnO2 films. This unexpected effect induces a dramatic drop in the electrical resistivity. Post-annealing treatment and XPS investigation indicate that the occurrence of surface-stabilized tin interstitials may be the primary reason for the unusual enhancement in conductivity. Cobalt doping not only generates the interstitial tin cations, but also stabilizes to a great extent their presence at the surface. This study may help to illumine new insight for the understanding of doping strategies, and offer a potential route for transport-related applications.

Porous SnO2/graphene composite thin films are prepared as anodes for lithium ion batteries by the electrostatic spray deposition technique. Reticular-structured SnO2 is formed on both the nickel foam substrate and the surface of graphene sheets according to the scanning electron microscopy (SEM) results. Such an assembly mode of graphene and SnO2 is highly beneficial to the electrochemical performance improvement by increasing the electrical conductivity and releasing the volume change of the anode. The novel engineered anode possesses 2134.3 mA h g–1 of initial discharge capacity and good capacity retention of 551.0 mA h g–1 up to the 100th cycle at a current density of 200 mA g–1. This anode also exhibits excellent rate capability, with a reversible capacity of 507.7 mA h g–1 after 100 cycles at a current density of 800 mA g–1. The results demonstrate that such a film-type hybrid anode shows great potential for application in high-energy lithium-ion batteries.Keywords: electrochemical spray deposition; graphene; lithium ion battery; thin films; tin oxide;

To improve the dehydrogenation properties of LiBH4, a novel hydrogen storage system, LiBH4–Li3AlH6, was synthesized by mechanical ball milling. The dehydrogenation/rehydrogenation properties of LiBH4–Li3AlH6 (molar rato: 1:1) composites were studied via thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The experimental results show that the hydrogen desorption capacity reaches 8.5 wt% and that the whole dehydrogenation is a three-step process: (1) a decomposition reaction Li3AlH6 → 3LiH + Al + 3/2H2, occurring at 160 °C; (2) formation of an intermediate product from 300 °C to 350 °C, and then subsequent transformation into Al, AlB2, and H2. (2LiBH4 + Al → [Li2B2AlH4] → x(AlB2 + 2LiH + 3H2) + (1 − x) [Li2B2AlH4], (0 < x < 1)); and (3) final dehydrogenation of LiH + Al → LiAl + 1/2H2, occurring at 415 °C, with sequential decomposition of the remaining intermediate ((1 − x)[Li2B2AlH4]→(1 − x)(AlB2 + 2LiH + 3H2), (0 < x < 1)). Furthermore, the dehydrogenated products can be rehydrogenated to LiBH4 at 8 MPa H2 and 400 °C.Highlights► A novel hydrogen storage system, LiBH4–Li3AlH6, was synthesized. ► The dehydrogenation/rehydrogenation mechanism of LiBH4–Li3AlH6 composite was studied. ► LiBH4–Li3AlH6 composite showed good hydrogen storage properties.

The effect of defects in the diluted magnetic semiconductor (DMS) of Fe and Na co-doped ZnO nanoparticles was investigated. Structural characterizations revealed that Fe and Na ions enter into ZnO lattice without any secondary phase. The ferromagnetic behaviors at room temperature were found in all samples, which are attributed to the exchange via electron trapped oxygen vacancies (F-center) coupled with magnetic Fe ions. With the increase of the Na concentration, the oxygen vacancy mediated ferromagnetic state is enhanced. The observed correlation between the Na concentration, the carrier concentration and the magnetization revealed the role of the defect in tuning the ferromagnetism in the ZnO-based DMS system.Highlights► A new defect was introduced by Na co-doping into ZnFeO by sol–gel method. ► The study of structure indicates the ZnFeNaO system remains wurtzite ZnO structure. ► Carrier density and oxygen vacancy concentration changed after Na doping. ► Enhanced ferromagnetism in ZnFeNaO was observed compared with ZnFeO. ► The ferromagnetism is attributed to the defect induced exchange interaction.

The glass forming ability and magnetic properties of Nd5Fe68 − xB23Mo4Yx (x = 0, 2, 4, 6) alloys prepared by copper mold casting technique have been studied. Amorphous rods with a diameter of 2 mm were obtained in the Nd5Fe64B23Mo4Y4 alloy. After annealing for 10 min at 1013 K, the Nd5Fe64B23Mo4Y4 alloy showed optimal hard magnetic properties with the coercivity of 764.2 kA/m, remanence of 0.6 T and maximum energy product of 57.3 kJ/m3, respectively. The enhanced magnetic properties can be ascribed to the strong exchange coupling among the magnetically soft α-Fe (25–30 nm), Fe3B (30–35 nm) and hard Nd2Fe14B (40–50 nm) grains present in the magnet microstructure. Large size bulk nanocomposite magnets with sound magnetic properties make the Nd–Fe–B–Mo–Y alloy system a promising candidate for industrial applications.Highlights► Synthesis of Nd5Fe68 − xB23Mo4Yx bulk amorphous alloys by copper mold casting method. ► 4 at.% Y addition greatly improves the glass forming ability of the alloy system. ► 2 mm diameter rod permanent nanocomposite magnet was obtained after annealing. ► Optimal magnetic properties were achieved with annealed Nd5Fe64B23Mo4Y4 alloy at 1013 K for 10 min.

Electrical conductivity of SnO2-based oxides is of great importance for their application as transparent conducting oxides (TCO) and gas sensors. In this paper, for the first time, an unusual enhancement in electrical conductivity was observed for SnO2 films upon zinc doping. Films with Zn/(Zn + Sn) reaching 0.48 were grown by pulsed spray-evaporation chemical vapor deposition. X-Ray diffraction (XRD) shows that pure and zinc-doped SnO2 films grow in the tetragonal rutile-type structure. Within the low doping concentration range, Zn leads to a significant decrease of the crystallite size and electrical resistivity. Increasing Zn doping concentration above Zn/(Zn + Sn) = 0.12 leads to an XRD-amorphous film with electrical resistivity below 0.015 Ω cm at room temperature. Optical measurements show transparencies above 80% in the visible spectral range for all films, and doping was shown to be efficient for the band gap tuning.

High-quality uniform SnO2 thin films were successfully prepared by pulsed-spray evaporation chemical vapor deposition (PSE-CVD) method, using a cost-efficient precursor of nBu2Sn(acac)2. The volatility and stability of nBu2Sn(acac)2 were studied through thermogravimetric-differential thermal (TG-DTA) analysis and mass spectrometry, indicating the good adaptability for the CVD process. Deposition of SnO2 films was made in the range of 250–450 °C to investigate the effect of substrate temperature on their structural and physical properties. The film growth activation energy changes from 66.5 kJ/mol in the range of 250–330 °C to 0 kJ/mol at 330–450 °C, suggesting the change of the rate-limiting step from surface kinetics to diffusion control. All films possess the rutile-type tetragonal structure, while a change of preferred orientation from (1 1 0) to (1 0 1) plane is observed upon the increase of the deposition temperature. The different variation of the nucleation and growth rates with the deposition temperature is proposed to explain the observed unusual change of crystallite size. A significant deterioration of the electrical conductivity was observed upon the increase of the deposition temperature, which was tentatively attributed to the non-specific decomposition of the precursor at high temperature leading to carbon contamination. Optical measurements show transparencies above 80% in the visible spectral range for all films, while band gap energy increases from 4.02 eV to 4.08 eV when the deposition temperature was raised from 250 °C to 450 °C.Highlights► A new cost-efficient precursor of nBu2Sn(acac)2 was applied for the deposition of SnO2 films. ► The study of volatility and stability of nBu2Sn(acac)2 indicates the good adaptability for the CVD process. ► The different variation of the nucleation and growth rates with the deposition temperature is proposed to explain the observed unusual change of crystallite size. ► A systematic study of physical properties of as-deposited SnO2 was conducted considering the effect of deposition temperature.

Low-temperature reactive pulsed laser deposition (PLD) was used to prepare iron nitride films. The textured γ′-Fe4N films with (0 0 1)-orientation were deposited on Si (1 0 0) substrate with Fe buffer layer at a substrate temperature as low as 150 °C. The (0 0 1)-oriented γ′-Fe4N film grew on the Fe buffer layer with a 3.5-nm thick amorphous interlayer, which eliminated the lattice mismatch stress between them. The films showed a columnar granular morphology with an average lateral grain size of approximately 110 nm. The films exhibited good soft magnetic properties with a high in-plane Mr/Ms value of 0.84. The magneto-optic Kerr effect results indicated an in-plane magnetic isotropy and confirmed the high remnant ratio of the γ′-Fe4N films.Research highlights► γ′-Fe4N films have gained increasing interests as potential application as spintronics magnetic devices. This is the first time that the (0 0 1)-oriented γ′-Fe4N film was deposited on Si (1 0 0) substrate at relatively low deposition temperature of 150 °C by pulsed laser deposition. ► The films exhibited good soft magnetic properties with a high in-plane Mr/Ms value of 0.84. In addition, the magneto-optic Kerr effect measurement demonstrated an in-plane magnetic isotropy of the film. ► The low temperature deposition of (0 0 1)-oriented γ′-Fe4N films on silicon substrate is important for the applications in magnetic devices and for the integration of magnetic devices into silicon technology.

A series of [(Fe1−xCox)72Mo4B24]94Dy6 (x = 0.1, 0.2, 0.3, 0.4 and 0.5 at.%) bulk metallic glasses (BMGs) in rod geometries with critical diameter up to 3 mm were fabricated by copper mold casting method. This alloy system exhibited good thermal stability with high glass transition temperature (Tg) 860 K and crystallization temperature (Tx) 945 K. The addition of Co was found to be effective in adjusting the alloy composition deeper to eutectic, leading to lower liquidus temperature (Tl). The [(Fe0.8Co0.2)72Mo4B24]94Dy6 alloy showed the largest supercooled liquid region (ΔTx = Tx − Tg = 92 K), reduced glass transition temperature (Trg = Tg/Tl = 0.622) and gamma parameter (γ = Tx/(Tg + Tl) = 0.424) among the present system. Maximum compressive fracture strength of 3540 MPa and micro-Vickers hardness of 1185 kg/mm2 was achieved, resulting from the strong bonding structure among the alloy constituents. The alloy system possessed soft magnetic properties with high saturation magnetization of 56.61–61.78 A m2/kg and coercivity in the range of 222–264.2 A/m, which might be suitable for application in power electronics devices.Research highlights▶ Synthesis of large size BMGs with [(Fe1−xCox)72Mo4B24]94Dy6 (x = 0.1, 0.2, 0.3, 0.4 and 0.5 at.%) alloy system. ▶ High GFA with large values of ΔTx (80–92 K), Trg (0.609–0.622) and γ (0.415–0.424). ▶ Maximum compressive fracture strength up to 3540 MPa and Hv of 1185.

The corrosion behavior of Al100 − xCux (x = 15, 25, 35, 45 at.%) doped Nd–Fe–B magnets has been investigated in 0.005 M H2SO4 solution using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. It was found that the corrosion resistance first improves with the increase of copper content, reaches a maximum at x = 35 and thereafter decreases. The existence of optimal corrosion resistance in the Al65Cu35 doped magnets is attributed to both the increase of chemical stabilization and the optimization of distribution/morphologies of (Pr, Nd)-rich intergranular phases. Addition of Al55Cu45 shows poorer corrosion resistance mainly due to coarsening of intergranular phases that, in turn, led to increasing the amount of active reaction channel at the triple junction of the matrix phase.Research highlights▶ Corrosion resistance of Al100 − xCux doped magnets depends on the Cu content. ▶ Al65Cu35 doped magnet has optimal corrosion resistance. ▶ Corrosion is related to stabilization and distribution of intergranular phases.

To improve the corrosion resistance and magnetic properties, Al85Cu15 (at.%) compound powders were added to (Pr, Nd)14.8Fe78.7B6.5 sintered magnets as grain boundary modifiers. The corrosion resistance was found to be remarkably improved by small additions of Al85Cu15 powders. When 1.2 wt% Al85Cu15 was added, the corrosion rate of magnets in humid environments was reduced by two orders of magnitude. This is partly due to the stability enhancement of the (Pr, Nd)-rich intergranular phase by Cu and Al. In addition, the occurrence of the Cu-rich phase ((Pr, Nd)22Fe56Cu10Al2O10), whose open-circuit potential is higher than the (Pr, Nd)-rich intergranular phase, may be another reason for the improvement of the corrosion resistance. Furthermore, the magnetic properties of (Pr, Nd)14.8Fe78.7B6.5 were also improved by adding 0.3–1.2 wt% Al85Cu15. Optimum addition amount was 0.6 wt%. The improvement of the magnetic properties may be related to the microstructural modification and the increase of magnet density.

Very thin Fe85.8Si9.6Al5.6 (wt.%) nanocrystalline flakes have been fabricated from melt-spun ribbons by a high-energy planetary ball-milling method. A large aspect ratio (>10:1) has been successfully obtained after milling for 70 h, resulting in improved permeability of high frequencies. The ordered D03 superlattice coexisting with α-Fe(Si, Al) matrix in the melt-spun ribbons vanishes with prolonged milling, but recovers after short-time annealing, also resulting in an improvement in magnetic properties.

A new approach was developed to prepare ferromagnetic–nonmagnetic functionally graded material (FGM) via slip casting in a gradient magnetic field based on the distinct difference in magnetic susceptibility between a ferromagnetic particle and a nonmagnetic one. ZrO2–Ni FGM with a continuously changing composition was successfully fabricated using this method. The microstructure, elemental distribution and microhardness variation of the sintered ZrO2–Ni samples prepared within and without the magnetic field were investigated.

•SnO2 films exhibiting room temperature ferromagnetism (RTFM) have been prepared on Si (001) by pulsed laser deposition.•Growth temperature, oxygen pressure and annealing affect the growth of SnO2 films.•Both the concentration and location of the oxygen vacancies play critical roles in the magnetization.SnO2 films exhibiting room temperature ferromagnetism (RTFM) have been prepared on Si (001) by pulsed laser deposition. The saturation magnetization (Ms) of the films experiences a decreasing trend followed by increasing with the growth temperature increased from RT to 400 ℃. The growth temperature affects both the concentration and the location of the oxygen vacancies as the origin of the RTFM. With lower growth temperatures (<300 ℃), more oxygen vacancies exist in the inner film for the samples with less crystallinity, resulting in enhanced magnetism. Higher deposition temperature leads to less oxygen vacancies in the inner film but more oxygen defects at the film surface, which is also beneficial to achieve greater magnetism. Various oxygen pressures during growth and post-annealing have also been used to confirm the role of oxygen vacancies. The study demonstrates that the surface oxygen defects and the positively charged monovalent O vacancies (VO+) in the inner film are the origin of the magnetism in SnO2 films.

Ce substitution level in Nd-Fe-B magnets has been significantly increased via the binary main phase (BMP) approach, i.e. sintering the mixture of Ce-free and Ce-containing RE2Fe14B (RE, rare earth) powders. REFe2 phase that forms in the high Ce-containing Nd-Ce-Fe-B magnets has been considered to be harmful to magnetic performance due to its soft magnetism. In this work, we found that REFe2 phase with lower melting point than the 2:14:1 phase plays positive role on optimizing the microstructure and retaining magnetic performance of the Nd-Ce-Fe-B BMP magnets. The wettability of 2:14:1 phase can be improved by sintering above the melting point of REFe2 phase, which promotes densification of the magnet and the formation of continuous and smooth grain boundary (GB) phases. This contributes to the weakened short-range exchange coupling between adjacent grains, hence ensures superior magnetic performance of BMP magnets to the single main phase (SMP) ones with the same average composition. As a result, magnetic properties of Br = 12.4 kG, Hcj = 9.0 kOe and (BH)max = 36.7 MGOe can be obtained even when 45 wt % Ce substitutes for Nd in the BMP magnets.

Organometallically prepared AlH3 and as-received Al powders were mixed with MgH2 to improve the dehydriding and rehydriding properties of MgH2. Thermal analysis shows that the onset dehydriding temperature of MgH2 is reduced by 55 °C (or 25 °C) when mixed with AlH3 (or Al). The destabilization of MgH2 is attributed to the formation of Mg–Al alloys through the reaction between MgH2 and Al. Isothermal dehydriding measurements demonstrate that AlH3 and Al both improve the dehydriding kinetic of MgH2 to some extent, and it only takes 44 min for MgH2 + AlH3 (5.4 h for MgH2 + Al) to release 60% of the hydrogen of MgH2 at 300 °C, but 8.6 h are required for as-milled MgH2. The apparent activation energy for the dehydriding of MgH2 is reduced from 174.6 kJ mol−1 for as-milled MgH2 to 154.8 and 138.1 kJ mol−1 for MgH2 mixed with Al and AlH3 respectively; this is responsible for the improvement in the dehydriding kinetics of MgH2. Despite this, AlH3 is better in destabilizing MgH2 than the as-received Al for the fact that Al* formed in situ from the decomposition of AlH3 is oxide-free on the particle surfaces, which effectively increases the chemical activity of Al*. Furthermore, the brittleness of AlH3 makes it easier to mix MgH2 with AlH3, which would result in uniform distributions of Mg and Al and shortening of the diffusion length. Concerning the reversibility, at 300 °C and 5 MPa H2 and MgH2 are fully recovered in the dehydrided MgH2 + Al, and MgH2 + AlH3 samples after rehydriding for 10 h. The rehydriding kinetic of MgH2 is significantly enhanced for the dehydrided MgH2 + AlH3, but not in the case of the MgH2 + Al.

Electrical conductivity of SnO2-based oxides is of great importance for their application as transparent conducting oxides (TCO) and gas sensors. In this paper, for the first time, an unusual enhancement in electrical conductivity was observed for SnO2 films upon zinc doping. Films with Zn/(Zn + Sn) reaching 0.48 were grown by pulsed spray-evaporation chemical vapor deposition. X-Ray diffraction (XRD) shows that pure and zinc-doped SnO2 films grow in the tetragonal rutile-type structure. Within the low doping concentration range, Zn leads to a significant decrease of the crystallite size and electrical resistivity. Increasing Zn doping concentration above Zn/(Zn + Sn) = 0.12 leads to an XRD-amorphous film with electrical resistivity below 0.015 Ω cm at room temperature. Optical measurements show transparencies above 80% in the visible spectral range for all films, and doping was shown to be efficient for the band gap tuning.