固相-熔盐法非平衡骤热骤冷工艺制备高纯BiFeO3及性能

采用固相-熔盐法非平衡骤热骤冷工艺(SSR-MSS-SHCN)制得粒径分布均匀、高纯度的BiFeO₃粉体。通过XRD、FT-IR、TG-DSC、VSM及SEM等对样品物相结构、性能及形貌进行表征。结果表明, 骤热骤冷的非平衡工艺更有利于提高BiFeO₃纯度。单一的固相法或熔盐法采用骤热骤冷非平衡工艺合成的产物均含有Bi₂₅FeO₃₉和/或Bi₂Fe₄O₉杂相。固相-熔盐法骤热骤冷非平衡工艺制得了几近单相的高纯度BiFeO₃粉体。高纯度BiFeO₃粉体磁性能室温呈反铁磁性, 而低温呈弱铁磁性和/或超顺磁性, 而非自旋玻璃态。

Fabrication and Properties of Highly Pure BiFeO3 Using A Method of Solid State Reaction-molten Salt Synthesis with Non-equilibrium Process

High pure Bismuth ferrite (BiFeO₃) powders were prepared by a solid state reaction-molten salt synthesis method (SSR-MSS method) using shock heating and chilling non-equilibrium process (SHCN process). The structure, morphology and electromagnetic properties were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscope (FTIR), Thermogravimetry-Differential Scanning Calorimetry (TG-DSC) and Vibrating Sample Magnetometer (VSM). The results indicated that SHCN process was better to get higher purity of BiFeO₃ powders than conventional equilibrium process (C process), but still has a certain number of impurity phases like Bi₂₅FeO₃₉ and/or Bi₂Fe₄O₉ as found in the products prepared by either SSR-SHCN process or MSS-SHCN process. In contrast, single-phase BiFeO₃ powders could be obtained by SSR-MSS-SHCN process. The micro-nanoscale BiFeO₃ powders presented antiferromagnetism, superparamagnetism, and/or weak ferromagnetism behavior at room temperature, but not spin-glass state at low temperature (5 K).