Effect of ceria on properties of yttrium-doped strontium titanate ceramics

The comparison of SrTi0.98Nb0.02O3–δ-CeO2 and SrTi0.98Nb0.02O3–δ-YSZ composites for use in SOFC anodes

“…This appears to be especially important for STNb2-CeO 2 , because the resistance to layer cracking and delamination during reductionoxidation decreases with the increasing CeO 2 concentration [8,12]. Koutcheiko et al [8] reports that it is caused by the contraction of the CeO 2 lattice parameter in less reducing atmospheres.…”

“…This appears to be especially important for STNb2-CeO 2 , because the resistance to layer cracking and delamination during reductionoxidation decreases with the increasing CeO 2 concentration [8,12]. Koutcheiko et al [8] reports that it is caused by the contraction of the CeO 2 lattice parameter in less reducing atmospheres. The thermal expansion coefficient (TEC) of composites consisting of yttrium-doped strontium titanate and cerium oxide is very similar to the TEC of YSZ (10.3× 10 −6 K −1 [8,17]), at least in the temperature range 50-1000°C and in air [8].…”

“…Koutcheiko et al [8] reports that it is caused by the contraction of the CeO 2 lattice parameter in less reducing atmospheres. The thermal expansion coefficient (TEC) of composites consisting of yttrium-doped strontium titanate and cerium oxide is very similar to the TEC of YSZ (10.3× 10 −6 K −1 [8,17]), at least in the temperature range 50-1000°C and in air [8]. However, the value of the TEC increases in a reducing atmosphere, and the higher the concentration of CeO 2 in the composite, the higher the TEC of composite material [8].…”

“…Both doped and undoped ceria are mixed ionic and electronic conductors at low oxygen partial pressure. CeO 2-x has high values of oxygen surface exchange and presents an ntype conductivity of about 1 S/cm at 900°C in oxygen partial pressure of 10 −18 atm [8]. In this paper only results obtained for undoped ceria will be presented in order to avoid additional complications from possible reactions between Gd 2 O 3 and SrTiO 3 phases.…”

“…Due to its high electronic conductivity, doped SrTiO 3 may be competitive to Ni-YSZ as a SOFC anode material. However, at present the ionic conductivity and the catalytic properties of SrTiO 3 are not sufficient for anode application [8]. Moreover, the SrTiO 3 anode tends to delaminate from the electrolyte surface [9,10].…”