In <sub> 2 </ Sub> The O <sub> 3 </ Sub> Control Synthesis Of Nano-structured Materials, The Reaction Mechanism And The Nature Of The Study

This paper is focused on the controlled synthesis of indium oxide (In₂O₃) nanostructures, n-type semiconducting oxide of III-VI compounds, through liquid-phase chemistry routes. Investigations are based on three aspects: controlled synthesis, formation mechanism, and properties and applications. The contents mainly include metastable corundum-type In₂O₃ nanotubes' preparation, size-controlling, formation mechanism and field-effect transistors (FETs) properties and the cubic In₂O₃ nanocrystals' preparation, size-controlling, formation mechanism and optical and gas-sensing properties, intending to study the intrinsic controlling mechanism of the nanocrystal formation and their effects on the devices' applications. 1. Preparation of InOOH and In₂O₃ nanotubes under mild reaction conditions and their electronic propertiesInCl₃·4H₂O is added into anhydrous ethanol. Formamide and sodium dodecyl benzene sulfonate (SDBS) are used as the additives. After the solution is heated at 140 ℃ for a setting time, tubular InOOH is separated by centrifugation, and washed with deionized water. Fourier Transform Infrared (FT-IR) spectrum, Thermo-gravimetric analysis (TGA) and Transmission Electron Microscopy (TEM) observation indicate that in the initial stage part of the counterions of SDBS are replaced by In³⁺ ions and forming intermediate complex contained water and stabilized by dodecylbenzene-sulfonate. The complex dissolves slightly in ethanol and then self-assembles to form the lamella-like particles containing nanowires. Upon extended heating, the lamella particles tend to be discrete and form tubular structure. X-ray diffractions (XRD) indicate two reactions occur: hydrolysis forming In(OH)₃ nanorods and dehydrolysis forming InOOH. Over time as reactants are consumed, the ehydrolysis progressively become dominant and the hydrolysis gradually weakens. In this process, the preformed In(OH)₃ slowly dissolves due to its larger solubility compared with that of the InOOH, and then the heterogeneous nucleation and growth of new InOOH occurs on the surface of the In(OH)₃ nanorods. When all the In(OH)₃ in the inner part has dissolved, InOOH nanorods with larger diameter and hollow...