均匀共沉淀法制备钛酸钡-钡铁氧体核-壳结构粒子

用均匀共沉淀法制备了钛酸钡-钡铁氧体核-壳粒子, 研究了沉淀反应温度、尿素/金属离子摩尔比值(R)和BaTiO₃浓度对核-壳粒子形貌和结构的影响, 探讨了钛酸钡-钡铁氧体核-壳粒子在焙烧时的形成过程及其磁性能. 采用透射电子显微镜(TEM)、X射线衍射(XRD)分析仪对钛酸钡-钡铁氧体前驱物核-壳粒子及钛酸钡-钡铁氧体核-壳粒子的形貌和结构进行了表征, 采用振动样品磁强计(VSM)研究了钛酸钡-钡铁氧体核-壳粒子的磁性能. 结果表明: 当沉淀反应温度为100 °C, R为180, BaTiO₃浓度为2.5 g·L^-1时, 金属离子沉淀完全, 得到的钛酸钡-钡铁氧体前驱物核-壳粒子包覆层均匀、完整、光滑, 厚度约为10 nm. 过高的温度和R值都会导致大量独立颗粒杂质的生成; 随着BaTiO₃浓度的增大, 包覆层厚度有减小的趋势. 当焙烧温度为900 °C时, 壳层中开始形成BaFe₁₂O₁₉相, 其形成过程为晶态的α-Fe₂O₃和BaCO₃首先生成中间相BaFe₂O₄, 然后由BaFe₂O₄和α-Fe₂O₃反应得到最终的BaFe₁₂O₁₉. 当焙烧温度为1000 °C时, 壳层完全转化为BaFe₁₂O₁₉相. 随着焙烧温度从900 °C升高到1000 °C, 所得BaTiO₃-BaFe₁₂O₁₉核-壳粒子的饱和磁化强度从16.5 A·m²·kg^-1增加到39.5 A·m²·kg^-1, 矫顽力从340 kA·m^-1略微降低到316 kA·m^-1.

Preparation of BaTiO3-BaFe12O19 Core-Shell Structure Particles by Homogeneous Coprecipitation

BaTiO3-BaFe12O19 core-shell structure particles were obtained using the homogeneous coprecipitation method. The effects of temperature, molar ratio of urea to metal ions (R), and BaTiO3 concentration on the morphology and structure of the core-shell particles were investigated. The mechanism of formation for the BaTiO3-BaFe12O19 core-shell structure particles and their magnetic property were also discussed. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the morp...