| Summary: | The atomic layer deposition of gallium and indium oxide was investigated on mesoporous silica powder and compared to the related aluminum oxide process. The respective oxide (GaO<sub>x</sub>, InO<sub>x</sub>) was deposited using sequential dosing of trimethylgallium or trimethylindium and water at 150 °C. In-situ thermogravimetry provided direct insight into the growth rates and deposition behavior. The highly amorphous and well-dispersed nature of the oxides was shown by XRD and STEM EDX-mappings. N<sub>2</sub> sorption analysis revealed that both ALD processes resulted in high specific surface areas while maintaining the pore structure. The stoichiometry of GaO<sub>x</sub> and InO<sub>x</sub> was suggested by thermogravimetry and confirmed by XPS. FTIR and solid-state NMR were conducted to investigate the ligand deposition behavior and thermogravimetric data helped estimate the layer thicknesses. Finally, this study provides a deeper understanding of ALD on powder substrates and enables the precise synthesis of high surface area metal oxides for catalytic applications.
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