Phase assembly and electrical conductivity of spark plasma 4 sintered CeO 2 – ZrO 2 ceramics 5

10 Abstract CexZr1-xO2 (x = 0.10, 0.16 and 0.33) nano11 crystalline powders were obtained by a two-step synthesis 12 technique and sintered by spark plasma sintering (SPS). As 13 consequence of the reduction of Ce to Ce species by 14 carbon in the graphite environment in SPS, phase assem15 blies including tetragonal, monoclinic and pyrochlore 16 phases were generated in the ceramics during the sintering 17 process. The electrical conductivity was highly dependent 18 on phase assembly and atmosphere (N2, H2 and O2). A 19 significant decrease in the activation energy was noticed in 20 the ceramics with high pyrochlore content when measuring 21 the conductivity in H2 atmosphere, consequence of the 22 strong reduction promoted in these ceramics during the 23 measurement. Equal conduction behavior with similar 24 activation energy was observed in all the ceramics when 25 measuring in O2 atmosphere. 6