Authors: C.H. Xu, S.Q. Shi and Q. Tang
Affilation: The Hong Kong Polytechnic University, Hong Kong
Pages: 54 - 57
Keywords: nanoparticles, thermal oxidation, Antimony oxide
Antimony (Sb) oxide can be used as catalyst, retardant, fining agent, and optical material. Recently, hydrous Sb oxide was found to have high proton conductivity, which is likely to be a promising humidity-sensing material. Oxide nano-particles have increasingly attracted interest over the past decade due to the possibilities of novel properties compared with bulk materials. It is reported recently that the synthesis of Sb oxide nano-particles can be done by the chemical method, in which SbCl3 and NaOH are used as starting materials. Another reported method of synthesis of Sb oxide nano-particles is vapor condensation, which includes the three steps: melting Sb by laser, oxidizing vapor Sb and condensing Sb oxide. However, the mixture of Sb and Sb oxide nano-particles is usually obtained in this method. Sb oxide nano-particles are synthesized by thermal oxidation in this research. Pure Sb is put in the middle of a tube furnace in compressed air at a pressure of 1 atm. with a constant flow rate. The furnace temperature at the position of samples is set at about 550oC, which is less than the melting point of Sb (630oC) but higher than the melting point of Sb3O5 oxide (525oC). Compared with metal Sb, Sb oxide shifts with gas flow. Si wafer, glass and Al foil are used as substrates and the substrates are put downstream of gas flow to collect Sb oxide. The collected Sb oxides are examined with scanning electron microscopy and transmission electron microscopy. Sb oxide obtained in this method shows nano-particles structures, as shown in Fig. 1. The phase of the collected Sb oxide is characterized with X-ray diffractometer. The mechanism of synthesis of Sb oxide particles is analyzed, based on the experiment results. The effects of substrate materials on nan-oxide structure are discusses.