Microstructure and electrical conductivity of 10% Yb-doped SrCeO3 ceramics.

As a candidate material for hydrogen separation, Yb-doped SrCeO 3 has attracted increasing attention in recent decades. In the present study, Yb-doped SrCe 0.9 Yb 0.1 O 3-α ceramics were prepared by the dry pressing and sintering approach, with the microstructure evolution and the micro morphology investigated. It was indicated that the ceramics sintered in air were of a pure perovskite structure, and that the sintering temperature had a significant effect on the growth of ceramic grains. The average grain size increased from 1 ​μm to 10 ​μm with an increase in sintering temperature from 1300 to 1500 ​°C. Further investigation of the thermodynamics and kinetics of grain growth revealed that the grain boundary diffusion was the main driving force of grain growth during solid phase sintering, with a grain growth index of 4 and an activation energy of approximately 61.23 ​kJ ​mol−1. These results illustrate an obvious tendency of grain size growth. By electrochemical workstation with different atmospheres the effects of sintering temperature on the conductivity were characterized in the temperature range of 700–900 ​°C. The electrical conductivities σ of SrCe 0.9 Yb 0.1 O 3-α ceramics in different atmospheres were as follows: σ(wet hydrogen) ​> ​σ(dry hydrogen) ​> ​σ(dry air) ​> ​σ(wet air). In the test atmosphere containing water and hydrogen the conductivity of protons increased with increasing temperature because of the protons jump between lattices in the form of interstitial hydrogen ions or bare protons. [Display omitted] • After sintering, Yb was completely dissolved in SrCeO 3 , and the Yb doped SrCeO 3 had a pure perovskite structure. Cell parameters of Yb doped SrCeO 3 were increased compared with SrCeO 3. • The radial shrinkage of 10% Yb doped SrCeO 3 ceramics increased from 7.29% at 1300 ​°C to 11.95% at 1500 ​°C. The results of sintering kinetics illustrated that the grain growth index of ceramics was 4, which indicated that the grain growth is mainly from the grain boundary diffusion. The activation energy of grain growth was about 61.23 ​kJ ​mol−1. • At 700–900 ​°C, the electrical conductivity of SrCe 0.9 Yb 0.1 O 3-α ceramics in different atmospheres was as follows: σ(wet hydrogen) ​> ​σ(dry hydrogen) ​> ​σ(dry air) ​> ​σ(wet air). [ABSTRACT FROM AUTHOR]