Power ramp reactive flash sintering of the Na+ superionic conductor Na3Zr2Si2PO12

Reactive Flash Sintering (RFS) is explored for the simultaneous reaction and densification of Na 3 Zr 2 Si 2 PO 12 directly from multiphase powders. By applying an AC electric field under power-ramp control, RFS enables phase formation and densification within minutes at a furnace temperature of 700°C, significantly below conventional conditions. Samples processed at 150 mW∙mm –3 for 15 min (ramp rate of 30 mW∙mm -3 ∙min -1 ) exhibit a total conductivity of σ total =1.14±0.11 mS∙cm –1 at 35°C and activation energy of E a =0.30±0.01 eV. In contrast, conventionally processed samples (reaction at 1100°C, 6 h, followed by separate sintering step at 1250°C, 6 h) show lower conductivity (0.75±0.08 mS∙cm –1 ) and higher activation energy (0.35±0.01 eV). Conventional processing under a Na-rich environment, achieved using a sacrificial powder bed, yields σ total and E a values equal to those obtained by RFS. These results highlight RFS potential as a rapid, energy-efficient route for fabricating high-performance solid electrolytes.