Microstructural and electrical characterization of Nb-doped SrTiO₃-YSZ composites for solid oxide cell electrodes

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• 作者：B.R. Sudireddy ; ^{bhsu@risoe.dtu.dk} ; P. Blennow ; K.A. Nielsen
• 关键词：Nb-doped SrTiO3 ; Ceramic electrode ; Microstructure ; Diffusion ; Electrical conductivity
• 刊名：Solid State Ionics
• 出版年：2012
• 期刊代码：96_01672738
• 类别：ch
• 出版时间：28 May, 2012
• 卷：216
• 期：Complete
• 页码：44-49
• 文件大小：1059 K

摘要

Nb-doped SrTiO₃ (Sr_{1 鈭?#xA0;x}Ti_0.9Nb_0.1O₃, x = 0.01 and 0.06, henceforth known as STN) and 8 mol%Y₂O₃ stabilized ZrO₂ (8YSZ) composites were prepared by mixing them in different volume fractions between 10 vol.%and 50 vol.%of 8YSZ. The composites were compacted into pellets, sintered and evaluated for phase stability, phase compatibility, microstructure and electrical conductivity. Microstructural analysis of the STN-8YSZ composites revealed that above 30 vol.%of 8YSZ, the percolation of the STN phase was extremely limited. Phase analysis by X-ray diffraction showed no clearly detectable secondary phases. However, microstructural analysis revealed segregation and formation of Nb enriched particles in the 50 vol.%8YSZ composite. Chemical analysis by energy dispersive spectroscopy (EDS) also showed the inter-diffusion of elements (especially Ti from STN and Zr from 8YSZ) from both phases on small length scales. The DC electrical conductivity measurements on the STN-8YSZ composites showed a drastic decrease in conductivity when more than 10 vol.%of 8YSZ was used in the composite. The initial metallic conductivity behavior changed to semiconducting type for more than 30 vol.%8YSZ, confirming the percolation limit observed by the microstructural analysis.