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Synthesis of Group III Oxyhydroxides and Their Properties

Author: ZhanBaoQing
Tutor: CuiLiang；ZhangJian
School: Jilin University
Course: Condensed Matter Physics
Keywords: Hydrothermal Nanocrystals Spectrum X-ray diffraction
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 42
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Abstract


Metal oxyhydroxides are of considerable significance in the fields of catalysis, absorption, fluorescence materials and electrochemistry, etc. However, up to date, fewer attempts have been devoted to the synthesis of metal oxyhydroxide nanoparticles, compared with metal oxides.Recently, Mg (OH)2 and MnOOH have been successfully obtained by pulsed laser ablation and hydrothermal reaction, respectively. Like In (OH) 3 and InOOH, GaOOH, AlOOH is another important kind of hydroxides. It can be used as vaccine adjuvant, catalyst in the oxidation of iodide and shows applications in biological field . More importantly, conventional chemical methods for synthesis of Al2O3Ga2O3 and In2O3 often involve decompositions of AlOOH, GaOOH, InOOH. Al2O3, Ga2O3 and In2O3 are important semiconducting materials with various applications as a transparent conducting oxide, optical emitter for UV, and as gas sensors. In this paper, we demonstrate that AlOOH, GaOOH, InOOH and In (OH) 3 nanocrystals could be successfully fabricated in large quantities through a facile hydrothermal synthetic method under mild conditions. The structure of the products was examined by X-ray diffraction. The morphology ofα-GaOOH was characterized using TEM (Hitachi-8100), and selected area electron diffraction (SAED) was further performed to identify the structure of the products. Fourier transform infrared spectra (FTIR) measurements were performed in the 400-4000 cm-1 range for samples dispersed in KBr pellets. Absorption spectra were monitored by a shimadzu UV-3150 spectrometer and photoluminescence spectra (PL) were recorded at room temperature.1. In this paper, we successfully fabricated flake-like AlOOH nanocristals, platelet-like GaOOH nanocrystals and rod-like InOOH crystals by a facile hydrothermal synthetic method under base conditions. The XRD patterns of the as-prepared samples showed that all the reflection peaks can be readily indexed to orthorhombic phases. GaOOH phase with lattice parameters a=4.516 ?, b=9.750 ? and c=2.965 ?. AlOOH phase with lattice parameters a=2.868 ?, b=12.227 ? and c=3.700 ?. InOOH phase with lattice parameters a=5.26 ?, b=4.56 ? and c=3.27 ?.2. The morphology of samples frabricated by the experiments was characterized using TEM (H-8100).TEM images showed AlOOH nano-flakes with 20nm-50nm and 100nm-150nm, GaOOH nano-platelets with 60nm-120nm and 200-300nm in short and long axes. SEM(S-4800) observations also indicate the products are mostly made up of nanoplatelet-like form, which agrees well with the TEM results.The images of InOOH showed rod-like InOOH nanocrystals with 1um-2um in length.3. The FTIR spectra of samples confirmed that the existence of Al2O, Ga2O, In2O and Al-OH Ga-OH, In-OH bending modes. The ultraviolet absorption of GaOOH was at 241nm and InOOH was at 309nm.PL measurements were made at excitation wavelength of 220nm at room temperature. The PL spectrums of GaOOH, InOOH showed all have several emission bands with maxium at 343nm and 355nm.

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