蒸发冷凝法制备超细LaB_6纳米粉末及表征

Preparation and Characterization of Ultrafine La B6Nanopowder by Evaporative Condensation Method

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。

Uhrafine LaB6 nanopowder with grain size around 40 nm was prepared by evaporative condensation method at the first time. The phase composition, morphology, microstructure and morphological evolution were systematically characterized and analyzed by X-ray diffraction （XRD） , field emission scanning electron microscopy （FESEM） , high-resolution transmission electron microscopy （HRTEM） and other methods. The results showed that the uhrafine nanopowder was CsCl-type crystal structure, and no other impurity phase was found. Scanning electron microscopy （SEM） results showed that the powder had an average grain size about 40 nm, the re- sults were consistent with the Scherrer formula, and the morphologies were cubic, hexagon and spherical coexist. HRTEM results re- vealed the microstructure evolution of LaB6 nanopowder. HRTEM image of fast Fourier transform （FFY） analysis showed that ultrafine LaB6 nanopowder were mainly composed of （100） and （110） crystal plane, and the corresponding crystal plane spacing was 0. 422 and 0. 294 nm, respectively. In addition, TEM images revealed the complete evolution of crystalline morphology, such as simple rectangle nested in the irregular sphere, hexagon and cube, which fully confirmed that the grain had different growth speeds along different crystal planes during the cooling crystallization.