Abstract
Densification of antimony‐doped tin oxide (ATO) ceramics without sintering aids is very difficult, due to the volatilization of SnO2, formation of deleterious phases above 1000°C, and poor sintering ability of ATO particles. In this paper, monodispersed ATO nanoparticles were synthesized via sol‐gel method, and then ATO nanoceramics with high density were prepared by spark plasma sintering (SPS) technology using the as‐synthesized ATO nanoparticles without the addition of sintering aids. The effect of Sb doping content on the densification was investigated, and the densification mechanisms were explored. The results suggest that ATO nanoparticles derived from sol‐gel method show good crystallinity with a crystal size of 5–20 nm and Sb is incorporated into the SnO2 crystal structure. When the SPS sintering temperature is 1000°C and the Sb doping content is 5 at.%, the density of ATO nanoceramics reaches a maximum value of 99.2%. Densification mechanisms are explored in detail.
Highlights
Because of their high electrical conductivity combined with chemical stability and corrosion resistance, antimony-doped tin oxide (ATO) materials are widely used in numerous applications such as catalytic and gas-sensing applications to monitor toxic gas emissions, as electrodes in the glass industry and as transparent conductive oxide (TCO) films [1,2,3,4]
The high density of SPSconsolidated ATO ceramics can be attributed to three factors: (a) monodispersed ATO nanoparticles with little amount of Sb segregation at the surface provide high sintering potential and high surface activation; (b) low temperature sintering of spark plasma sintering (SPS) avoids the need for sintering aids and prevents the formation of deleterious intermediate phases and the decomposition of the ATO system, and the fast sintering rate reduces the evaporation of SnO2; and (c) semiconducting ATO nanoparticles enable more current to pass through the sample during sintering and SPS discharge in the void spaces enhances the mass transport, which further enhances densification
Antimony is incorporated into the SnO2 crystal structure in concentrations of 1 at.%, to 10 at.% and the ATO nanoparticles show good crystallinity with crystallite sizes on the order of 5–20 nm
Summary
Because of their high electrical conductivity combined with chemical stability and corrosion resistance, antimony-doped tin oxide (ATO) materials are widely used in numerous applications such as catalytic and gas-sensing applications to monitor toxic gas emissions, as electrodes in the glass industry and as transparent conductive oxide (TCO) films [1,2,3,4]. The sintering problem is further complicated by the high vapor pressure of SnO, the formation of deleterious intermediate phases, and decomposition of the ATO system at temperatures above 1000∘C [8]. Adding additives such as ZnO, CuO, and MnO2 can promote densification by a liquid-phase mechanism [9,10,11], but the secondary phases formed in these cases adversely affect the electrical conductivity. The relative density (92.4%) was enhanced compared with the density of ATO ceramics sintered by conventional sintering technique (61.3%), but it is still too low for a target used to prepare TCO films using magnetron sputtering method. The densification mechanisms associated with SPS consolidation of bulk ATO ceramics were investigated
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