Tuesday, 31 May 2022: 16:40
West Meeting Room 218 (Vancouver Convention Center)
Oxygen-ion conductors with superior performance have been sought in the fields of energy conversion and storage.[1] Bi2O3-based ionic conductors which exhibit the highest known oxygen-ion conductivity have got attention for the next-generation solid electrolytes.[2] However, at intermediate temperatures below ~ 600 °C, their conductivity degrades rapidly owing to the cubic-to-rhombohedral phase transformation. Here, we demonstrate that grain boundary engineering can preserve the superior ionic conductivity of stabilized Bi2O3. To investigate the microstructural effect on stability, epitaxial and nano-polycrystalline model films of Er0.25Bi0.75O1.5 were fabricated by pulsed laser deposition. Interestingly, the grain boundary-free epitaxial film significantly improved the stability of the cubic phase while severe degradation is observed in conductivity of its polycrystalline counterpart. First-principles calculations revealed that thermodynamic stability of the cubic phase with respect to the rhombohedral counterpart is reduced near grain boundaries. These findings suggest novel aspects into the development of highly durable superionic conductors via physical manipulation of microstructure.
References
[1] E. D. Wachsman, K. T. Lee, Science 2011, 334, 935.
[2] B.-H. Yun, K. J. Kim, D. W. Joh, M. S. Chae, J. J. Lee, D.-w. Kim, S. Kang, D. Choi, S.-T. Hong, K. T. Lee, Journal of Materials Chemistry A 2019, 7, 20558.