Characterisation of Antimony and Antimony-Bismuth Oxides Synthesised By Precipitation Technique.

Antimony oxide exists in several different phases and this single oxide has generated considerable interest in applications such as polyethylene terephthalate (PET) production and semiconductor devices manufacturing. In this study, antimony oxide and antimony bismuth oxide have been prepared via precipitation and coprecipitation technique, respectively. The influence of various preparation parameters (starting material, precipitating agent, precipitation route and pH) on the prepared antimony oxide has been investigated. The characteristics of the samples (antimony oxide and antimony bismuth oxide) were determined by Differential Thermogravimetry/Thermogravimetric Analysis (DTG/TGA), Powder X-ray Diffraction Analysis (XRD), Fourier Transform Infrared Analysis (FTIR), Brunauer-Emmett-Teller Surface Area Measurements (BET) and Scanning Electron Microscopy (SEM). Extent of reduction of antimony bismuth oxide was investigated by employing Temperature-Programmed Reduction in H2 (TPR) technique. Starting material and precipitation route have influenced the formation of the final products which have given the different surface area. By using antimony(III) acetate (raw material) via forward precipitation route, a single phase of Sb2O3 senarmontite phase with high surface area can be obtained. As the concentration of precipitating agent, NaOH is increased, the formation of antimony oxide phase changed from single phase to mixed phase which was vice versa with increasing of NH4OH concentration. The sample of high surface area with corresponding ultrafine particle could be achieved at optimum condition (0.6 M of NaOH concentration). The microstructural change of prepared antimony oxide was determined at various pH values. The pH change does not effect the formation of antimony oxides phases but led to the higher surface area as the pH increases. The evolvement of the antimony bismuth oxide phase occurred as the NH4OH concentration increases. The high surface area sample with small grain size can be obtained using 0.6 M NH4OH. This sample gave small amount of oxygen removal in accordance to TPR result.

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