Nanometric La0.9Sr0.1Ga0.8Mg0.2O3-x ceramic prepared by low-pressure reactive spark-plasma-sintering

It is proposed a processing route to obtain dense (>= 90%) nanometric La0.9Sr0.1Ga0.8Mg0.2O3-x (LSGM) electrolyte ceramic by reacting under spark-plasma-sintering (SPS) conditions a relatively poor mixture of intermediate powdered La/Sr- and Ga/Mg-based products synthesized separately by precipitation and hydrothermal methods, respectively. Samples with particle size of 9-20, 37-93, and 120-240 nm were measured from the electrical conductivity viewpoint. A fast transport path along grain boundaries was not observed and, a higher nano particle size improves total conductivity in our samples. Results suggest that it is necessary to make a clear distinction between particle size from microscopy observation and crystallite size from structural (e.g. XRD) measurements when looking at the general conductivity - grain size dependence. This dependence is complex and the use of an unconventional, far from equilibrium technique such as SPS might influence it. Currently, a good understanding is missing, but pending on materials, technology specifics and the complex relationship between them, some of the usually promoted ideas from literature such as the necessity of high mixing levels in the precursor powders, of high pressure application during sintering, of low particle size (nano) in the sintered ceramic for a higher conductivity, of high purity phase and so on require careful consideration. (C) 2010 Elsevier B.V. All rights reserved.