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PREPARATION OF TIN OXIDE
by H. TAIB(a,b)*and C.C. SORRELL(a)
(a)School of Materials Science and Engineering,
University of New South Wales, Sydney, NSW 2052, Australia
(b)Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia,
86400 Parit Raja, Batu Pahat, Johor, Malaysia
Abstract
Submicron tin oxide (SnO2) was obtained from the thermal decomposition of tin oxalate (SnC2O4) precipitated at room temperature from mixed solutions of tin (II) chloride and oxalic acid. The concentrations were in the range 0.04 M to 0.20 M and decomposition was done at 800oC for 1 hour.
The work was intended to focus on the effects of initial solution concentration on the particle size of the calcined SnO2. This was done by:
i) Increasing the oxalic acid concentration at fixed tin (II) chloride concentration
ii) Increasing the tin (II) chloride concentration at fixed oxalic acid concentration
The particle and agglomerate sizes of the calcined SnO2 also were assessed in terms of the morphology of the precipitated SnC2O4, which was calcined to SnO2.
The SnC2O4 morphology showed a mixture of individual elongated prisms and elongated prismatic intergrowths. However, the occurrence of the intergrowths did not correlate with the precipitation conditions.
After calcining, pure tetragonal SnO2 of consistent , spherical, individual, particle size of ~75 nm was observed, regardless of precipitation conditions. The consistent particle size probably is due to the low solution concentration range used.
Crushing and grinding the calcined SnO2 powders resulted in agglomerated platelets, with a mean diameter in the range ~0.5 micron. It is likely that surface water adsorption on the fine particles facilitated the establishment of plasticity, which allowed the deformation between mortar and pestle during grinding. There was no apparent relationship between the starting solution concentration, addition method, and SnO2 particle and agglomerate size.
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