α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 ...α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 particles. Kinetic studies on the bismuth oxidation at low-temperatures were carried out by TGA method. The results show that bismuth beads should be reunited and oxidized to become irregular Bi2O3 powders. The bismuth oxidation follows shrinking core model, and its controlling mechanism varies at different reaction time. Within 0-10 min, the kinetics is controlled by chemical reaction, after that it is controlled by O2 diffusion in the solid α-Bi2O3 layer. The apparent activation energy is determined as 55.19 kJ/mol in liquid-phase oxidation.展开更多
In this paper, the electrochemical synthesis method was used to prepare γ-Bi2O3. Ultrafine Bi metal powder was first synthesized by electrochemical method at room temperature in a single cell .The anode comprised the...In this paper, the electrochemical synthesis method was used to prepare γ-Bi2O3. Ultrafine Bi metal powder was first synthesized by electrochemical method at room temperature in a single cell .The anode comprised the sacrificial metal Bi; the cathode was Pt; the NaOH solution was used as the electrolyte. The ultrafine Bi metal powder had a special chemical reactivity. Then γ-Bi2O3 was prepared by the reaction of ultrafine Bi and NaOH solution. The effect of the concentration of NaOH solution, reaction temperature and additive were studied. The principle of the reaction was discussed. The component of the product was determined by atomic emission spectrometry and EDTA titration analysis. XRD, SEM ,TEM and DTA were employed for the characterization of the obtained products.展开更多
基金Project (2006BAB02B05-04- 01/02) supported by the National Key Technologies R&D Program of China
文摘α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 particles. Kinetic studies on the bismuth oxidation at low-temperatures were carried out by TGA method. The results show that bismuth beads should be reunited and oxidized to become irregular Bi2O3 powders. The bismuth oxidation follows shrinking core model, and its controlling mechanism varies at different reaction time. Within 0-10 min, the kinetics is controlled by chemical reaction, after that it is controlled by O2 diffusion in the solid α-Bi2O3 layer. The apparent activation energy is determined as 55.19 kJ/mol in liquid-phase oxidation.
文摘In this paper, the electrochemical synthesis method was used to prepare γ-Bi2O3. Ultrafine Bi metal powder was first synthesized by electrochemical method at room temperature in a single cell .The anode comprised the sacrificial metal Bi; the cathode was Pt; the NaOH solution was used as the electrolyte. The ultrafine Bi metal powder had a special chemical reactivity. Then γ-Bi2O3 was prepared by the reaction of ultrafine Bi and NaOH solution. The effect of the concentration of NaOH solution, reaction temperature and additive were studied. The principle of the reaction was discussed. The component of the product was determined by atomic emission spectrometry and EDTA titration analysis. XRD, SEM ,TEM and DTA were employed for the characterization of the obtained products.
