Wengang Liu

La-modification of multiferroic BiFeO3 by hydrothermal method at low temperature

This study reports the effect of La doping on structural, morphological and magnetic characteristics of BiFeO3 synthesized under mild hydrothermal conditions at 200°C for 16 h using the KOH concentration of 4 M. The as-synthesized powders of Bi1−xLaxFeO3 for x = 0.05, 0.10, and 0.15 were characterized by X-ray powder diffraction scanning electron microscope and the vibrating sample magnetometer. The formation mechanism of Bi1−xLaxFeO3 powders can be expressed by “dissolution-nucleation-crystallization” process. The magnetism of Bi1−xLaxFeO3 increased with increase of La content due mainly to increscent suppressing spiral magnetic structure and magnetic contribution of La.

Effect of processing on microstructure and electrochemical performance of silicon/disordered carbon/carbon nanotubes composites

As an anode material for lithium-ion batteries, silicon/disordered carbon/carbon nanotubes composites were prepared by a sucrose-aided combustion method using two different mixing methods, namely mechanical stirring and ball milling. In this study, sucrose was used as a carbon source. The as-prepared composites were characterized by means of X-ray diffraction, field emission scanning electron microscopy, and electrochemical impedance spectroscopy. Both composites contain silicon and a small amount of carbon as predominating phases. The SDC-M composite prepared using mechanical stirring shows higher cycle performance (834.8 mAh/g) and first charge/discharge efficiency (72.4%) than the SDC-B composite prepared using ball milling (cycle performance of 815.2 mAh/g and first charge/discharge efficiency of 68.8%). The difference in the electrochemical performances of the SDC-M and SDC-B composites can be attributed to the distribution of carbon nanotubes and silicon particles in the disordered carbon matrices, which was greatly affected by mixing method.