CeO2-based oxide materials find wide applications in fuel
cells, gas sensors and as a promoter in three-way catalyst
(TWC) for automotive exhaust control [1,2]. The ability of
CeO2 for promotion of water gas shift reaction, thermal
stability and its oxygen storage capacity makes it an ideal
promoter in TWC formulations [3]. The key to oxygen
storage capacity of CeO2-based materials is due to its
characteristic feature to shift between Ce4+ and Ce3+ in the
stable cubic fluorite structure, which in fact allows release
and transport of O2 ions. Varistors are electroceramic
devices that show nonlinear electrical property [4,5]. They
are widely used to protect electrical and electronic
equipment against transient overvoltages. The most commonly
used commercial varistors are ZnO-based compositions
[6]. It had been also already well established that the
electrical nonlinearity in polycrystalline ZnO ceramics
arises from grain boundary phenomenon. Though ZnO
shows excellent varistor property, the drawback is its high
breakdown field [6]. Low voltage varistors based on SrTiO3
[7] and SnO2–TiO2 systems [8–10] have already been
reported in the literature. In the case of SnO2–TiO2 solid
CeO2-based oxide materials find wide applications in fuelcells, gas sensors and as a promoter in three-way catalyst(TWC) for automotive exhaust control [1,2]. The ability ofCeO2 for promotion of water gas shift reaction, thermalstability and its oxygen storage capacity makes it an idealpromoter in TWC formulations [3]. The key to oxygenstorage capacity of CeO2-based materials is due to itscharacteristic feature to shift between Ce4+ and Ce3+ in thestable cubic fluorite structure, which in fact allows releaseand transport of O2 ions. Varistors are electroceramicdevices that show nonlinear electrical property [4,5]. Theyare widely used to protect electrical and electronicequipment against transient overvoltages. The most commonlyused commercial varistors are ZnO-based compositions[6]. It had been also already well established that theelectrical nonlinearity in polycrystalline ZnO ceramicsarises from grain boundary phenomenon. Though ZnOshows excellent varistor property, the drawback is its highbreakdown field [6]. Low voltage varistors based on SrTiO3[7] and SnO2–TiO2 systems [8–10] have already beenreported in the literature. In the case of SnO2–TiO2 solid
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