Cold sintering for Li <sub>1.5</sub> Al <sub>0.5</sub> Ge <sub>1.5</sub> (PO <sub>4</sub> ) <sub>3</sub> using LiNO <sub>3</sub> -LiOH as a transient solvent
Kenji Takashima, Yoshiki Iwazaki, Clive A. Randall
Abstract
Abstract The cold sintering process (CSP) is an innovative technique to densify ceramic powders at ultralow temperatures by applying uniaxial pressure and using a transient solvent. However, obtaining dense Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) ceramics, which have high ionic conductivity, by CSP has been a challenging subject, because incongruent dissolution from the powder to a solvent can happen during CSP, and that deteriorates the grain boundary. In this study, LiNO 3 -LiOH salt is used as the transient solvent to suppress the incongruent dissolution. LAGP ceramics densified by the CSP at 220 °C and 400 MPa for 5 h have no damage at the grain boundary. As the result, the total ionic conductivity reaches 1.9 × 10 −5 S cm −1 , which is the highest value ever reported among LAGP ceramics prepared by CSP only using inorganic materials.