Morphology controllable synthesis and characterization of gallium compound hierarchical structures via forced-hydrolysis method

To our best knowledge, β-Ga₂O₃ via hierarchical gallium precursors from nanoparticles to microrods was successfully synthesized for first time using the forced-hydrolysis method and the calcination process. We report the growth mechanism and formation of various morphological gallium precursors such as Ga₄(OH)₁₀SO₄ nanospheres and α-GaOOH microrods. The influence of the growth time on the crystal structure and its morphology was studied. The results indicate that the growth time played an important role in the transformation from amorphous to single-crystal structures. After calcination at 1000 °C for 1 h, well-crystallized and porous β-Ga₂O₃ microrods are formed. The enhanced broad blue emission of porous β-Ga₂O₃ microrods were related to defect band emission, such as oxygen vacancies and gallium-oxygen vacancy pairs. We propose that this oriented growth and transformation model may also be applicable to crystal growth and phase transformations and support the fabrication of other three-dimensional hierarchical materials, which is potentially important for a broad range of optoelectronic applications.