A New Preparation Pathway to Well-Defined In2O3 Nanoparticles at Low Substrate Temperatures

The structure and morphology of thin In 2 O 3 films deposited on NaCl(001) single-crystal cleavage faces and thin sapphire sheets has been studied by transmission electron microscopy techniques and scanning electron microscopy. Both the substrate temperature and the nature of the substrate proved to be crucial for the formation of crystalline and well-defined In 2 O 3 structures and morphologies. For In 2 O 3 films grown on single-crystal NaCl(001) faces, a gradual transition from a quasi amorphous small-grain structure after deposition at 298 K to well-oriented In 2 O 3 particles predominantly exhibiting pyramidal and octahedral shapes after deposition at 603 K has been observed. At the highest substrate temperatures, most particles were found to be oriented along a [001] zone axis and few particles in a [011] orientation. In contrast, depositing In 2 O 3 on sapphire sheets under otherwise identical experimental conditions does not result in well-facetted In 2 O 3 particles, but rather leads to rounded In 2 O 3 agglomerates with a rough surface structure.