Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in fast...Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.展开更多
Nano-SrB2O4 powder was prepared by solid-state reaction at room temperature followed by a subsequent calcination process. The highly productive method which can be operated easily confirms to the Green-chemistry princ...Nano-SrB2O4 powder was prepared by solid-state reaction at room temperature followed by a subsequent calcination process. The highly productive method which can be operated easily confirms to the Green-chemistry principles. The XRD patters demonstrate that the component of the as-obtained sample is SrB2O4 after calcination at 600℃. Differential thermal analysis and thermogravimetriy (DTA/TG) curves suggest the process of dehydration and crystal transition from Sr[B(OH)4]2 to SrB2O4·2H2O. SEM image of SrB2O4 shows that the particles are uniform and spherical with average size of 80 nm in diameter. Furthermore, the mechanism of reaction was discussed. The chemical reaction of the process is assumed to be acid-base neutralization reaction. The water generated from the acid-base neutralization reaction and the release of crystal water from Sr(OH)2·8H2O plays an essential role in the reaction system.展开更多
The solid state reduction reaction of Al-10 % CuO mixed powders during mechanical alloying was investigated using XRD, DTA and TEM. The CuO is believed to be gradually reduced by Al, and controlled by diffusion of ato...The solid state reduction reaction of Al-10 % CuO mixed powders during mechanical alloying was investigated using XRD, DTA and TEM. The CuO is believed to be gradually reduced by Al, and controlled by diffusion of atoms and ions. Reduced Cu spontaneously reacts with Al to form a metastable equilibrium of Al (Cu) with Al4Cu9 phase during ball-milling, instead of CuAl2 and Al(Cu), which is only observed after annealing.展开更多
Perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-σ （BSCFO） powders were synthesized using two methods, solid-state reaction （SSR） method and citrate-EDTA complexing method （CC-EDTA）. Then the powders were pressed to gree...Perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-σ （BSCFO） powders were synthesized using two methods, solid-state reaction （SSR） method and citrate-EDTA complexing method （CC-EDTA）. Then the powders were pressed to green disks of 19 nun in diameter and sintered at 1140℃ for 5 h. The shrinkage rate and relative density of the membranes prepared from the perovskite-type powders were determined and calculated, and the powders and derived membranes were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The resuits show that the shrinkage rates of the two kinds of disks are nearly the same （about 10%）. The disks prepared by the SSR method had a bigger grain size and lower relative density than those prepared by the CC-EDTA method. The conductivity of the membranes prepared by the SSR method was about 38 S/cm, higher than that of the membranes prepared by the CC-EDTA method, which was about 30 S/cm, at the same temperature of600℃.展开更多
The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. T...The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. The synthesis mechanism of the spinel LiMn2O4 was studied by TGA-DTA analysis. It is found that the reaction of Li2CO3 and MnO2 will occur at the temperature lower than 600 ℃ and MnO2 has self-catalysis function during the reaction. The results of XRD and SEM to the synthesized materials show that the LiMn2O4 phase is pure, with regular appearance and uniform granularity distribution. The electrochemical tests indicate that the spinel LiMn2O4 has perfect cycling performances and the cycling capacity still keeps at 109.6 mA·h/g after 5 cycles.展开更多
As a functional inorganic material, LiAlO2 was focused on widely, especially in the field of tritium breeder of fusion reactor. In this article, the proper reaction conditions and mechanism to synthesis the γ LiAlO2 ...As a functional inorganic material, LiAlO2 was focused on widely, especially in the field of tritium breeder of fusion reactor. In this article, the proper reaction conditions and mechanism to synthesis the γ LiAlO2 by solid state method are considered. In the experiments, it has been found that the phase of β and γ LiAlO2 are only produced by the reaction of LiOH and Al2O3, while the α and γ LiAlO2 can be obtained by the reaction of Li2CO3 and Al2O3. As compared with Li2CO3 and Al2O3 reacted at 900～1000℃ for the preparation of γ LiAlO2, the γ LiAlO2 can also be made by the reaction of LiOH and Al2O3 at some more lower temperatures that is due to the bulk diffuse mechanism. But the former can get better crystal and have smaller particles for the mechanism of surface fast reaction. As a result, the sub micron γ LiAlO2 powders with the diameter less than 0.3μm are obtained.展开更多
文摘Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.
文摘Nano-SrB2O4 powder was prepared by solid-state reaction at room temperature followed by a subsequent calcination process. The highly productive method which can be operated easily confirms to the Green-chemistry principles. The XRD patters demonstrate that the component of the as-obtained sample is SrB2O4 after calcination at 600℃. Differential thermal analysis and thermogravimetriy (DTA/TG) curves suggest the process of dehydration and crystal transition from Sr[B(OH)4]2 to SrB2O4·2H2O. SEM image of SrB2O4 shows that the particles are uniform and spherical with average size of 80 nm in diameter. Furthermore, the mechanism of reaction was discussed. The chemical reaction of the process is assumed to be acid-base neutralization reaction. The water generated from the acid-base neutralization reaction and the release of crystal water from Sr(OH)2·8H2O plays an essential role in the reaction system.
文摘The solid state reduction reaction of Al-10 % CuO mixed powders during mechanical alloying was investigated using XRD, DTA and TEM. The CuO is believed to be gradually reduced by Al, and controlled by diffusion of atoms and ions. Reduced Cu spontaneously reacts with Al to form a metastable equilibrium of Al (Cu) with Al4Cu9 phase during ball-milling, instead of CuAl2 and Al(Cu), which is only observed after annealing.
基金supported by the National High-Tech Research and Development Program of China (No. 2006AA11A189) the National Natural Science Foundation of China (No. 50730004)
文摘Perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-σ （BSCFO） powders were synthesized using two methods, solid-state reaction （SSR） method and citrate-EDTA complexing method （CC-EDTA）. Then the powders were pressed to green disks of 19 nun in diameter and sintered at 1140℃ for 5 h. The shrinkage rate and relative density of the membranes prepared from the perovskite-type powders were determined and calculated, and the powders and derived membranes were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The resuits show that the shrinkage rates of the two kinds of disks are nearly the same （about 10%）. The disks prepared by the SSR method had a bigger grain size and lower relative density than those prepared by the CC-EDTA method. The conductivity of the membranes prepared by the SSR method was about 38 S/cm, higher than that of the membranes prepared by the CC-EDTA method, which was about 30 S/cm, at the same temperature of600℃.
基金Project(9810 3 0 0 70 4)supportedbyNaturalScienceFoundationofLiaoningProvince China projectsupportedbyQing haiScienceandTechnologyFund(2 0 0 2 G 10 2 )
文摘The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. The synthesis mechanism of the spinel LiMn2O4 was studied by TGA-DTA analysis. It is found that the reaction of Li2CO3 and MnO2 will occur at the temperature lower than 600 ℃ and MnO2 has self-catalysis function during the reaction. The results of XRD and SEM to the synthesized materials show that the LiMn2O4 phase is pure, with regular appearance and uniform granularity distribution. The electrochemical tests indicate that the spinel LiMn2O4 has perfect cycling performances and the cycling capacity still keeps at 109.6 mA·h/g after 5 cycles.
文摘As a functional inorganic material, LiAlO2 was focused on widely, especially in the field of tritium breeder of fusion reactor. In this article, the proper reaction conditions and mechanism to synthesis the γ LiAlO2 by solid state method are considered. In the experiments, it has been found that the phase of β and γ LiAlO2 are only produced by the reaction of LiOH and Al2O3, while the α and γ LiAlO2 can be obtained by the reaction of Li2CO3 and Al2O3. As compared with Li2CO3 and Al2O3 reacted at 900～1000℃ for the preparation of γ LiAlO2, the γ LiAlO2 can also be made by the reaction of LiOH and Al2O3 at some more lower temperatures that is due to the bulk diffuse mechanism. But the former can get better crystal and have smaller particles for the mechanism of surface fast reaction. As a result, the sub micron γ LiAlO2 powders with the diameter less than 0.3μm are obtained.
