A new class of mesoporous single crystalline (MSC) material, Co(OH)2 nanoplates, is synthesized by a soft template method, and it is topotactically converted to dual-pore MSC Co3O4. Most mesoporous materials derived from the soft template method are reported to be amorphous or polycrystallined; however, in our synthesis, Co(OH)2 seeds grow to form single crystals, with amphiphilic block copolymer F127 colloids as the pore producer. The single-crystalline nature of material can be kept during the conversion from Co(OH)2 to Co3O4, and special dual-pore MSC Co3O4 nanoplates can be obtained. As the anode of lithium-ion batteries, such dual-pore MSC Co3O4 nanoplates possess exceedingly high capacity as well as long cyclic performance (730 mAh g(-1) at 1 A g(-1) after the 350th cycle). The superior performance is because of the unique hierarchical mesoporous structure, which could significantly improve Li(+) diffusion kinetics, and the exposed highly active (111) crystal planes are in favor of the conversion reaction in the charge/discharge cycles.
Novel hollow porous VO/C nanoscrolls are synthesized by an annealing process with the VO/octadecylamine (ODA) nanoscrolls as both vanadium and carbon sources. In the preparation, the VO/ODA nanoscrolls are first achieved by a two-phase solvothermal method using ammonium metavanadat as the precursor. Upon subsequent heating, the intercalated amines between the vanadate layers in the VO/ODA nanoscrolls decompose into gases, which escape from inside the nanoscrolls and leave sufficient pores in the walls. As the anodes of lithium-ion batteries (LIBs), such hollow porous VO/C nanoscrolls possess exceedingly high capacity and rate capability (904 mAh g at 1 A g) and long cyclic stability (872 mAh g after 210 cycles at 1 A g). The good performance is derived from the unique structural features of the hollow hierarchical porous nanoscrolls with low crystallinity, which could significantly suppress irreversible Li trapping as well as improve Li diffusion kinetics. This universal method of annealing amine-intercalated oxide could be widely applied to the fabrication of a variety of porous electrode materials for high-performance LIBs and supercapacitors.
TiC intermediate layers were formed on the surface of diamond particle with reaction of Ti powders in mixed molten NaCl-KCl salts. The copper/diamond composites with TiC-coated diamond particles were fabricated by pressure infiltration. Then the microstructure and thermal conductivity of the obtained copper/diamond composites were studied. The results showed the thermal conductivity of the composites with a density of 5.65 g/cm3reached 514 Wm-1K-1, which is much higher than with uncoated diamond. The TiC layers synthesized on diamond particles is shown to be an effective way to enhance the thermal conductivity of copper/diamond composite.
By the use of YH2 and NiO, oxide particles were introduced in Ni-base ODS alloys through reactive ball milling, which shows the advantages of energy-saving and uniform distribution of the oxide dispersion. The mophological and size evolution of ball milled powder were investigated, and the synthesized oxides were characterized. The results shows that the ball milled powder exhibits the feather of severe deformation. The disintegration of particles occurs after 10 h, and the balance of powder welding and fracturing is achieved around 25 h. the formation of Y2O3 with the size of 20~50 nm was confirmed by XRD and TEM results.
AlN powders were synthesized by carbothermal reduction method using a combustion synthesis precursor derived from aluminum nitrate (oxidizer), glucose (carbon source), and urea (fuel) mixed solution. Effects of carbon source content on the combustion temperature of solutions, the particle size and morphology of the precursors and the synthesized AlN were studied in detail. The results indicated that a regular variation in the particle size and morphology of precursors had been observed with the increasing molar ratio of glucose to aluminum nitrate (C/Al). The products prepared with (C/Al=8–12), calcined at 1500 oC for 2 h, could have completed the nitridation reaction, while the nitridation products prepared with (C/Al=4 and 16) are opposite. The nitridation products prepared with (C/Al=8–12), calcined at 1500 oC for 2 h, are comprised of well-distributed spherical particles of AlN with the average size ranging from 50 to 80 nm.
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