Lecture
Relationships between sintering method, microstructure and conductivity: the case of NASICON
Scandium-substituted NASICON (Na3.4Sc0.4Zr1.6Si2PO12) is a promising electrolyte material for sodium-ion solid
state batteries, with the highest ionic conductivity reported to date for a NASICON material. Low-temperature
densification and control of microstructure are important factors to enable the low-cost manufacturing of such
new battery type [1]. Non-conventional sintering techniques such as Field Assisted Sintering Technology / Spark
Plasma Sintering (FAST/SPS) and Cold Sintering are therefore investigated and compared to conventional free
sintering. FAST/SPS enables to get rapidly dense samples at lower temperatures than the ones required
by conventional sintering routes and with similar electrical properties. Cold sintering experiments, involving the
addition of aqueous solutions as sintering aids and high mechanical pressure, enable a moderate densification,
but at temperatures as low as 250 °C. Further heat treatments still below the conventional sintering temperature
increased the achieved density and ionic conductivity [2].
References:
[1] S. Naqash et al., Microstructure–conductivity relationship of Na3Zr2(SiO4)2(PO4) ceramics, Journal of the American Ceramic Society, 2019
[2] J. Pereira da Silva et al., Sintering of a sodium-based NASICON electrolyte: a comparative study between cold, field assisted and conventional sintering methods, Journal of the European Ceramic Society, 2019
