水热环境下磁场对BiFeO_3形貌和性能的影响

Effects of Magnetic Field on the Morphology and Properties of BiFeO_3 Synthesized by Hydrothermal Method

以Bi（NO3）3·5H2O和Fe（NO3）3·9H2O为反应原料,KOH为矿化剂,通过在碱浓度为2-7 mol/L、反应温度为140-220℃的磁场水热反应系统中保温1-12 h制备了Bi Fe O3粉体.研究发现,外加磁场可以拓宽合成纯相Bi Fe O3的碱浓度和反应温度范围,更易得到纯相铁酸铋粉体.SEM观测结果表明,通过改变磁场强度可有效控制Bi Fe O3粉体的颗粒尺寸及形貌：随着磁场的增强,Bi Fe O3的颗粒尺寸逐渐减小.随着颗粒尺寸的减小,其光催化活性增强.磁场下得到的粉体表现出较强的磁性,Raman散射中A1-2振动模式异常增强.

Abstract BiFeO3 powders were synthesized by hydrothermal method under different magnetic fields with KOH concentrations of 2-7 mol/L at 140-220℃ for 1-12 h, using Bi（NO3）3 · 5H2O and Fe（NO3）3 · 9H2O as reaction materials and KOH as the mineralizer. The external magnetic field expanded the experimen- tal range of alkali concentration and reaction temperature for the synthesis of pure BiFeO3 phase. SEM images showed that the magnetic field effectively reduced the BiFeO3 particle size. The results of photocatalytie experiment showed that the photoeatalytic activity of the BiFeO3 powders increased with decreasing particle size. The magnetization was increased and the intensity of A1-2 resonance mode in Raman spectra was enhanced for BiFeO3 prepared under mangetie field.