Scandia – Stabilized Zirconia: Effect of Dopants on Surface/Grain Boundary Segregation and Transport Properties

Abstract

The nanocrystalline samples of 10wt.%Scandia stabilized Zirconia (10ScSZ) and 1wt.%Ceria doped ScSZ (1Ce10ScSZ) prepared via co-precipitation route were characterized and compared to commercially available samples regarding their transport properties and electrical conductivity. The results of oxygen isotope experiments show that for Zirconia-based electrolytes, the rate of heteroexchange is lower than that for Samaria-doped Ceria. The results of Secondary Ions Mass Spectrometry (SIMS) indicate that all admixed components are present both in the surface layer and the bulk of the studied samples with pronounced segregation on the grain boundary. The highest total conductivity is observed for DKKK sample. In the range of 600-400°C the highest conductivity observed for synthesized nanocrystalline 1Ce10ScSZ sample is explained by the effect of segregated Scandia doped Ceria surface layers.

Mechanochemical synthesis and conducting properties of nanostructured rhombohedral scandia stabilized zirconia ceramics

“…This feature was explained by the chemical inhomogeneity, admixture of the monoclinic phase and traces of contaminants from steel milling media (∼0.1 wt%). In addition, silica traces segregated at grain boundaries strongly decrease the oxygen conductivity of SSZ ceramics as was shown in [15,16] and in our work [11].…”

“…The drawback of SSZ is conductivity decrease with annealing time (aging) due to ordering of vacancies accompanied by the martensitic phase transition of the cubic phase to a lower symmetry rhombohedral phase [3][4][5]. On the other hand, when SSZ is codoped with CeO 2 this unfavorable phase transition is suppressed making this material a very promising electrolyte for IT-SOFC [6][7][8][9][10][11][12]. The technique of powdered SSZ preparation determines the final conducting properties of sintered ceramics [11,12].…”

“…On the other hand, when SSZ is codoped with CeO 2 this unfavorable phase transition is suppressed making this material a very promising electrolyte for IT-SOFC [6][7][8][9][10][11][12]. The technique of powdered SSZ preparation determines the final conducting properties of sintered ceramics [11,12]. In our previous paper unusually high oxygen conductivity at low temperatures with E b ∼ E gb ∼ 0.85 eV was observed in nanostructured fluorite-related SSZ-based solid solutions (4-12% molar Sc) obtained by the mechanochemical approach from a technical grade ZrO 2 [13].…”

Flame spray synthesis and characterisation of stabilised ZrO2 and CeO2 electrolyte nanopowders for SOFC applications at intermediate temperatures

“…The conductivities of the 10SSZ and 10Sc1CeSZ were about 2-5 times higher than that of 10GCO and 8YSZ, respectively. Consistent to literature [20,21], a change in the slope of the conductivity was observed for 10Sc1CeSZ in the lower temperature region of 550°C, while 10SSZ still shows significant higher conductivities. In Table 4 total conductivity σ at the particular temperatures of 600°C and 800°C is compared to literature data.…”

Nanocomposite Catalysts for Steam Reforming of Methane and Biofuels: Design and Performance

“…In general, a better performance is provided by YSZ-containing catalysts (Sadykov et al, 2010b). Though more detailed studies are required for elucidating the exact role played by the rare-earth cations in determining catalytic properties of these nanocomposites, it is clear that observed trends are not determined by the oxygen mobility in doped zirconia particles which is higher for ScCeSZ (Smirnova et al, 2007). Hence, the most efficient promoter for Ni/YSZ -based composite catalyst is Pr(Sm)-doped ceria-zirconia in combination with Pt.…”