Yanjie Wang,Kiyoshi Nomura,Xin Liu,Alexandre I. Rykov,Changzi Jin,Tao Liu,Junhu Wang
Graphical Room-temperature ferromagnetism (RTFM) was found in 57 Fe-TiO 2 and 57 Fe/Sn-TiO 2 materials prepared by a soft-chemical solution method. Their magnetic properties were found to decrease with increasing degree of 57 Fe doping. Fe 3+ –oxygen vacancy (V O )–Fe 3+ centers are responsible for the observed RTFM. A series of 57 Fe-doped TiO 2 and 57 Fe/Sn-codoped TiO 2 materials were prepared by a soft-chemical solution process with various 57 Fe concentrations from 0.1 to 1.0 at.-% and a fixed Sn concentration of 2.0 at.-%. In this process, an aqueous H 2 O 2 solution reacts with iron and titanium or iron, tin, and titanium precursor compounds to produce peroxopolymetallic acids. The structures and magnetic properties of the products were characterized by magnetic-moment measurements, X-ray diffraction, and Raman and Mössbauer spectroscopy. The results showed that all samples consisted of a rutile phase (and a trace amount of anatase in 57 Fe-TiO 2 ). All samples exhibited hysteresis loops in the M – H curves, which demonstrated the presence of room-temperature ferromagnetism. In addition, their magnetic properties decreased with increasing degree of 57 Fe doping. Oxygen vacancies were considered to be responsible for the presence of ferromagnetism.
Shenyu Wang,Nannan Wu,Yuzhen Liu,Wei Liu,Jiurong Liu
The porous nanocomposites of TiO 2 with Fe 2 TiO 5 acting as anode materials for lithium-ion batteries (LIBs) are successfully fabricated via a solvothermal method followed by a sintering process. The porous TiO 2 /Fe 2 TiO 5 nanocomposites display a dominant pore size of ca. 30 nm and specific surface area of 38.0 m 2 g −1 , which can provide large contact area between electrolyte and electrode and shorten the diffusion distance of lithium-ion. Electrochemical examinations prove that the as-prepared TiO 2 /Fe 2 TiO 5 electrode material achieves a reversible capacity of 440.8 mAh g −1 at a current density of 100 mA g −1 after 400 cycles, and the capacities of 165.0, 115.3, and 66.4 mAh g −1 at the current densities of 200, 400, and 800 mA g −1 , respectively. Comparing with TiO 2 porous structure, the improved electrochemical performances of the porous TiO 2 /Fe 2 TiO 5 nanocomposites are mostly ascribed to the synergistic effect of TiO 2 acting as a cycling stable buffer and Fe 2 TiO 5 increasing the capacity of electrode during the charge-discharge processes.
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