Preparation And Characterization Of Semiconducting Indium-containing Compounds

Three indium-containing compounds including In₂O₃, InOOH, and In(OH)₃ were synthesized at 160–200°C via a solvothermal route. The products were characterized by XRD, FTIR, XPS, TEM, SEM, PL, UV–Vis, and photocatalysis. The results show that all the three kinds of samples have high purity and high crystalline perfection. The sizes of the dispersed In₂O₃ nanoparticles are in the range of 5–10 nm. The lengths of the In(OH)₃ nanocubes are in the range of 50–160 nm. Two kinds of typical structures, i.e., nanorods and dendrite-like microstructures, have diameters of ¹00 nm and lengths up to 800–1500 nm. Both In₂O₃ and InOOH have photoluminescence properties, and the band gap of In₂O₃ is 4.20 eV. In addition, the both kinds of compounds have excellent photocatalytic activities under ultraviolet light radiation. The effects of reaction parameters on the resulting product were investigated, including the reaction temperature, reaction time, the amount of NaAc, and the volume ratio of H2O and ethylene glycol, etc. The formation mechanisms of different structures corresponding to the three kinds of indium-containing compounds are discussed.Ntrogen-doped In₂O₃ nanoparticles were synthesized by the solvothermal method in a stainless steel autoclaveat above 200°C. The nitrogen-doping efficiency was comparatively investigated by different nitrogen source and the molar ratio of starting materials. The results show that the nitrogen-doping efficiency related to sodium azide is higher than that of sodium amide. The nitrogen-doping efficiency is increased with increasing the amount of the nitrogen source. As a result, the maximum weight percent of doping nitrogen is up to 3.6%.In(OH)₃ crystals in millimeter scale were prepared by a hydrothermal method. The samples were characterized by XRD, TG/DSC, EDS, and SEM. The results show that the maximum length of the typical as-synthesized In(OH)₃ crystals is about 1.5 mm. The crystals with smooth surface are composed of In(OH)₃ multiplates in nanometer scale. The reaction conditions were explored such as reaction temperature, reaction time, concentration of NaOH, and the kind and amount of inducing agents. It is found that the inducing agents play an important role in the formation of In(OH)₃ millimeter crystals. The formation mechanism of the In(OH)₃ crystals is tentatively discussed.