Spray-drying and fabrication of superionic conducting sodium rare-earth silicates

Abstract

Fine precursor powders of particle diameter of 0.50-7 μm and high surface area (9 m2/g) for superionic conducting Na5RESi4O12 (RE=Gd, Y) were successfully produced by spray-drying and an optimised calcination procedure. Using these powders, dense sinters (>98% of theoretical) with f{hook}(NGS) or f{hook}(NGS)=1.0 (the proposed parameter for purity) were obtained under normal sintering conditions. 300°C ionic resistivities were calculated from ac impedance and had values of 5.6 Ω cm with an activation energy for conduction of 4.5 kcal/mol for Na5GdSi4O12 and 7.7 Ω cm and 5.9 kcal/mol for Na5YSi4O12. These values were dependent on the f{hook}(NGS) or f{hook}(NYS). © 1985.