State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, PR China.
Chem Asian J. 2013 Sep;8(9):2189-95. doi: 10.1002/asia.201300433. Epub 2013 Jun 26.
By taking advantage of UV-Raman spectroscopy and high-resolution TEM (HRTEM), combined with the focused ion beam (FIB) technique, the transformation from GaOOH into α-Ga2O3 and then into β-Ga2O3 was followed. We found that the stepwise transformations took place from the surface region before developing into the bulk of single particles without particle agglomeration and growth. During the transformation from GaOOH into α-Ga2O3, the elimination of water vapor through the dehydroxylation of GaOOH resulted in the formation of micropores in the single particles, whilst maintaining their particle size. For the phase transformation from α-Ga2O3 into β-Ga2O3, the nucleation of β-Ga2O3 was found to occur at the surface defects and this process could be retarded by occupying these defects with a small amount of La2O3. By finely controlling the process of the phase transformation, the β-Ga2O3 domains gradually developed from the surface into the bulk of the single particles without particle agglomeration. Therefore, the surface structure of the α-Ga2O3 single particles can be easily tuned and a particle with an α@β core-shell phase structure has been obtained.
通过利用紫外拉曼光谱和高分辨率透射电子显微镜（HRTEM），结合聚焦离子束（FIB）技术，我们跟踪了 GaOOH 向 α-Ga2O3 再向 β-Ga2O3 的逐步转变。我们发现，在没有颗粒团聚和生长的情况下，单颗粒的体相之前，其表面区域经历了逐步转变。在 GaOOH 向 α-Ga2O3 的转变过程中，GaOOH 的脱羟作用会除去水蒸气，从而在单颗粒中形成微孔，同时保持其颗粒尺寸。对于从 α-Ga2O3 向 β-Ga2O3 的相转变，发现在表面缺陷处开始形成 β-Ga2O3 的成核，而通过用少量 La2O3 占据这些缺陷可以延缓这一过程。通过精细控制相转变过程，β-Ga2O3 畴逐渐从单颗粒的表面向体相发展，而没有颗粒团聚。因此，α-Ga2O3 单颗粒的表面结构可以很容易地进行调整，并获得了具有α@β核壳相结构的颗粒。
