Nano- and Microstructure Design by Mechanochemical Approach of Ceramic Ionic Composites on the Base of SSZ

Abstract

Two series of Sc-stabilized zirconia nanostructured ceramic composites were prepared from mechanochemical origin nanopowders. The first series was obtained by reaction sintering, and the second one by conventional sintering of ceramic powders prepared mechanical activation route. Ceramic samples were studied by complex impedance method and characterized by XRD, SEM with EDX microanalysis. Dense nanostructured ceramics with high conductivity at operation temperature for IT SOFC 900-1000 K were obtained by sintering at 1673 K. The ceramic composites contain mainly cubic phase with minor tetragonal and monoclinic phases. The ordered cracking of grains near the surface with a size of blocks ~20 nm was observed. Cracking near surface and nanostructuring both results from relaxation of mechanical strains related to misfit in volume transformations under cooling of cubic matrix and embedded tetra/monoclinic nanograins. Nano- and microstructure design of composites by mechanochemical ceramic method may become a promising approach in solid state ionics.

Nano- and Microstructure Design by Mechanochemical Approach of Ceramic Ionic Composite Zr0.88Sc0.12O1.94/ZrO2

“…Super-high conductivity at lower temperatures was related to nanocomposite structure. Moreover, we observed in composite with general composition Zr 0.86 Sc 0.12 Y 0.02 O 1.93 conducting properties a small better than in regular ceramics from commercially available powder Zr 0.89 Sc 0.1 Ce 0.01 O 1.95 from DKKK Corporation, Japan [4]. High conducting properties in the obtained ceramic specimens contained from cubic, tetragonal and monoclinic phases can be related to mechanical strains around ZrO 2 -nanosized grains.…”

“…The aims of our work are: 1) the enhancement mechanochemical synthesis procedure of nanopowders for applications in above mentioned ceramic nanocomposites with composition Zr 0.88 Sc 0.12 O 1.94 /ZrO 2 ; 2) optimization of nano-and microstructure in ceramic composite to increase conducting properties at working temperature T ~ 1000 K. The best conductivity was obtained in composites with minimal content of tetragonal phase [4]. So, the study of yttria-less compositions will be presented.…”

“…2. We established in [4] the negative influence to conducting properties of ionradicals like ZrO 2+ which formation at high energy milling is possible. So, the enhanced procedure of nanocomposite preparation by mechanochemical approach will be presented.…”