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Ta-doped Li 7 La 3 Zr 2 O 12 (Ta-LLZO) solid electrolyte ceramics were synthesized by solid-state sintering, spark plasma sintering (SPS) and SPS plus heat-treatment (two-step method) using LiOH·H 2 O, La 2 O 3 , ZrO 2 and Ta 2 O 5 as the raw materials. The Ta-LLZO samples prepared from these three routes are all in cubic phase structure. However, the solid-state method results in Ta-LLZO samples with different particle sizes and porous morphology, while the samples prepared by SPS route contain fewer internal voids and smaller particle size. The two-step method not only retains the high compactness of SPS samples, but also the increment of grain size. The SEM results demonstrate that Ta-LLZO sintered by the two-step method shows optimal electrical properties. And the total ionic conductivity is 4.6×10 −3 S cm −1 at 150°C and the activation energy is calculated to be 0.38 eV.

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Spark plasma sintering (SPS) is an advanced sintering technique because of its fast sintering speed and short dwelling time. In this study, TiB2, Y2O3, Al2O3, and different contents of B4C were used as the raw materials to synthesize TiB2‐B4C composites ceramics at 1850°C under a uniaxial loading of 48 MPa for 10 min via SPS in vacuum. The influence of different B4C content on the microstructure and mechanical properties of TiB2‐B4C composites ceramics are explored. The experimental results show that TiB2‐B4C composite ceramic achieves relatively good comprehensive properties and exceptionally excellent flexural strength when the addition amount of B4C reaches 10 wt.%. Its relative density, Vickers hardness, fracture toughness, and flexural strength reach to 99.20%, 24.65 ± .66 GPa, 3.16 MPa·m1/2, 730.65 ± 74.11 MPa, respectively.

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