Synthesis of Cubic In₂O₃ by a Liquid Plasma Method without Chemical Additives

Abstract

Cubic In(OH) 3 crystals were prepared by a liquid plasma method at 6 kV and 55 mA using an H-cell. The solution pH in the cathode increased with the reaction time up to 15 min due to proton reduction, which promoted the deprotonation of In aqua complexes. In(OH) 3 was formed by the deprotonation of these complexes during proton reduction. After 15 min, the pH in the cathode cell was significantly decreased, which was ascribed to proton transfer from the anode to the cathode. pH measurements showed that a pH difference between the cathode and anode cells developed during the reaction. Nucleation and crystal growth were monitored via high-resolution transmission electron microscopy and selected area electron diffraction analysis of samples prepared with different reaction times. Initially, small amorphous particles were formed by Ostwald ripening, and these particles rearranged to form rods with 50−90 nm lengths. Cubic In(OH) 3 crystals formed via the oriented attachment of the rods. Finally, cubic In 2 O 3 crystals were prepared by calcining the In(OH) 3 samples. Photoluminescence emission peaks corresponding to green and orange emissions were observed for the In 2 O 3 prepared by calcining the In(OH) 3 samples. Further, XPS analysis revealed oxygen defects in the In 2 O 3 nanocubes.

Microplasmas for Advanced Materials and Devices

“…f) PL spectra of cubic In 2 O 3 NPs synthesized with varying time using microplasma‐assisted liquid phase method. Reproduced with permission . Copyright 2016, American Chemical Society.…”

“…Indium oxide In 2 O 3 with a relatively wide bandgap of about 3.0 eV is very useful for many applications including solar energy conversion, sensing devices, photochemical reactions, and optoelectronic devices . In 2 O 3 NPs were successfully fabricated using microplasma‐liquid processing . The optical properties of the NPs can be controlled by adjusting the plasma synthesis time and precursor concentrations (Figure f) …”

“…In 2 O 3 NPs were successfully fabricated using microplasma‐liquid processing . The optical properties of the NPs can be controlled by adjusting the plasma synthesis time and precursor concentrations (Figure f) …”

“…On the other hand, in the liquid‐phase microplasma synthesis, the shapes of In 2 O 3 NPs were controlled by the reaction time. The NP shape can be transformed from spherical particles at short reaction times (10 min), to rods at middle reaction times (15 min), to sheets at long reaction times (70 min), and even to cubes at very long reaction times (240 min) . The shapes of ZnO NSs have been controlled by varying the capping agents during the microplasma‐assisted liquid‐phase synthesis .…”

Quantitative spectrochemical analysis of solution plasma in aromatic molecules

“…Several essential approaches of the SP process in both aqueous and organic solutions have been intensively considered for water purification and sterilization, polymerization, surface modification, and nanoparticles synthesis . Recently, in our laboratory, the SP process as a simple and environmentally friendly method was applied to synthesize nanoparticles and nanostructures with controlled size, content, and crystallinity, and composite nanocarbon materials with a defined function such as the removal of toxic substances or high electrical conductivity .…”