engleski

Application of sol-gel method in the synthesis of gallium(III)-oxide

Precipitations by hydrolysis of gallium(III)-isopropoxide and from aqueous GaCl3 solution by addition of aqueous tetramethylammonium hydroxide (TMAH) solution were utilized to obtain gallium(III)-oxide precursors. The precursors thus formed and the samples obtained upon heating these precursors at high temperatures were analysed by XRD, FT-IR and TEM. Amorphous phase (dominant) and nanosized alpha-GaOOH particles (several nanometers in size) were obtained by addition of hot water and TMAH solution to the solution of gallium(III)-isopropoxide dissolved in 2-propanol. A completely amorphous precipitate was obtained by hydrolysis of gallium(III)-isopropoxide with pure water at room temperature, and upon heating this precipitate at 500 oC the nanosized beta-Ga2O3 particles (size ~10 to 20 nm) were obtained. On the other hand, alpha-GaOOH particles, as a single phase, were obtained by precipitation from aqueous GaCl3 solution with addition of aqueous TMAH solution. These alpha-GaOOH particles transformed at 500 oC to alpha-Ga2O3 as a single phase. Upon heating at 900 oC, in all cases only beta-Ga2O3 was detected. The size and morphology of the particles in the samples investigated depended on the starting chemicals and the conditions of the experiment. A differences in the mechanism of the precipitation by hydrolysis of gallium(III)-isopropoxide or the precipitation from aqueous solution of GaCl3 by addition of strong organic alkali (TMAH) were suggested.

Sol-gel; alpha-GaOOH; Alpha Ga2O3; beta-Ga2O3; XRD; FT-IR; TEM

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