Electrical and mechanical properties of Sm2O3 doped Y-TZP electrolyte ceramics

This study aimed to investigate the effects of Sm2O3 dopant on the sintering behavior, electrical and mechanical properties of the sintered Y-TZP ceramic samples. X-ray diffraction (XRD) results show that Sm2O3 could be dissolved in Y-TZP to form Sm2O3 and Y2O3 co-doped t-ZrO2 (SY-TZP). The additions of Sm2O3 (0.5-3 mol%) to Y-TZP does not affect its phase structure, and the SY-TZP sintered samples maintain a stable tetragonal structure. According to the scanning electron microscopy (SEM) results, it is found that the addition of Sm2O3 can promote the sintering densification with a uniform grain growth, and dense ( > 98% of theoretical) electrolyte ceramics with grain size of 10 mu m were obtained after sintering at 1550 degrees C. Electrical and mechanical properties testing results indicate that the mechanical properties of Y-TZP are not significantly changed by a small amount of Sm2O3 (0.5 mol%), but the conductivity was improved obviously. The conductivity of 0.5 mol% Sm2O3 doped Y-TZP (0.5SY-TZP) is 0.02 S cm(-1), and the activation energy is 1.012 eV at 800 degrees C. When the doping amount is more than 1%, the mechanical properties of Y-TZP changes. With the increase of Sm2O3 content, the hardness and flexural strength of sintered ceramics are reduced, but the conductivity increased. 3SY-TZP sample which sintered at 1550 degrees C for 4 h shows the highest conductivity, the conductivity and activation energy reaches to 0.026 S cm(-1) and 0.863 eV at 800 degrees C, respectively. Overall, sintering behavior and electrical properties analysis results suggest that Sm2O3 could be used not only as an effective sintering aid but also can as co-dopant on the optimization of electrical properties for yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) electrolytes.