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采用蒸发冷凝法制备了颗粒度为40 nm左右的超细La B6纳米粉末。通过X射线衍射仪(XRD),场发射扫描电镜(FESEM),高分辨透射电镜(HRTEM)等方法对超细纳米粉末物相,形貌,微观结构及形貌演变过程进行系统地表征分析。结果表明,超细粉末物相为Cs Cl-型晶体结构,未发现其他杂质相的出现。FESEM观察结果表明,粉末平均晶粒度约为40 nm,与Scherrer公式计算结果符合较好,晶粒形貌为简单立方、六角、球形共存。与此同时HRTEM结果揭示了超细La B6纳米粉微观结构演变过程,HRTEM图谱的快速傅里叶变换(FFT)分析表明超细La B6纳米粉末主要由(100)和(110)晶面组成,晶面间距分别对应0.422,0.294 nm。此外,TEM系列图谱再现了产物完整的结晶形貌演化,非规则球形中嵌套简单长方、六角,立方,充分证明降温结晶过程中晶粒沿不同晶面生长速度不同。
Ultrafine La B6 nanopowder with particle size of about 40 nm was prepared by evaporation condensation method. The phase, morphology, microstructure and morphological evolution of the ultrafine nanopowder were systematically characterized by XRD, FESEM and HRTEM. The results show that the ultrafine powder phase is CsCl-type crystal structure, and no other impurity phase is found. FESEM observations show that the average grain size of the powder is about 40 nm, which is in good agreement with the Scherrer formula. The grain morphology is simple cubic, hexagonal and spherical. At the same time, the results of HRTEM revealed the microstructure evolution of ultrafine La B6 nanostructures. Fast Fourier Transform (FFT) analysis of HRTEM spectra showed that ultrafine La B6 nanostructures consisted mainly of (100) and (110) Interplanar spacing corresponding to 0.422,0.294 nm. In addition, the TEM series of images reproduce the complete evolution of the crystalline morphology of the product. The irregularly-shaped spheres are nested in simple rectangles, hexagons and cubes, which fully demonstrate that the growth rates of crystal grains along different crystal planes during the cooling crystallization process are different.