Spark plasma sintering of Ruddlesden-Popper Ca2-xDyxMnO4 ceramics: Impact on thermoelectric and mechanical performance

n-type Dy-doped Ca2MnO4 powders with the Ruddlesden-Popper structure were synthesized by the combustion method and sintered by conventional sintering and spark plasma sintering (SPS). Conventional sintering fails to densify Ca2MnO4, but the addition of Li2O proves to be a highly effective sintering additive, albeit with a detrimental impact on electrical conductivity. In contrast, SPS at 850 degrees C for 1 min yields nanostructured, nearly fully dense samples, demonstrating superior outcomes. The dimensionless figure of merit ZT reaches 0.02 at 750 degrees C. Additionally, the best sample exhibits a remarkable hardness value of 10.7 GPa, underlining the excellent mechanical properties achieved through this innovative approach.