Low Temperature Synthesis of Lanthanum Silicate Apatite Type by Modified Sol Gel Process

Abstract:

Rare earth silicate apatite type is a very important and promising material for application as an electrolyte in IT-SOFC (Intermediate Temperature Solid Oxide Fuel Cell). Lanthanum silicate apatite, La_9,33Si₆O₂₆, exhibits high conductivity and has high efficiency, long term stability, fuel flexibility, low emissions and relatively low cost compared to yttria stabilized zirconia (YSZ - yttria stabilized zirconia), at temperatures between 600 to 800 °C. One of the problems of YSZ is its high operating temperature which results in long starting times and problems of mechanical and chemical compatibility. The interest of investigating lanthanum silicate apatite as an electrolyte is to overcome the problems caused by high temperature operation required by YSZ electrolyte. In the present study, sol-gel method was used to synthesize La_9,33Si₆O₂₆. Initially, the reagents (sodium silicate and lanthanum nitrate) were mixed to obtain colloidal silica. Then, this gel containing lanthanum nitrate was thermally treated to allow the melting of lanthanum nitrate salt distributed on colloidal silica. The aim of this study was to verify if this method permits the formation of La_9,33Si₆O₂₆ pure apatite phase, in order to obtain fine powders and uniform particles for further processing and obtaining a ceramic body.

• Periodical: Advanced Materials Research (Volume 975)
• Pages: 143-148
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.975.143
• Online since: July 2014
• Authors: Agatha Matos Misso, Daniel Ricco Elias, Fernando dos Santos, Chieko Yamagata*
• Keywords: Apatite-Type, La_9.33Si₆O₂₆, Lanthanum Silicate, SOFC, Sol Gel, Synthesis

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