Charged Grain Boundaries in Ionic Ceramics
Prof. R. E. García
Purdue University, USA
Time & Place
Mon, 11 Jun 2018 16:00:00 NZST in 120, College of Engineering Meeting Room, Engineering CORE
Experimental studies aimed to understand the bottlenecks that control the properties in ionic ceramics for energy applications indicate that grain boundaries impact (positively or negatively) the macroscopic charge conductivity for applications such as solid oxide fuel cells, rechargeable lithium-ion batteries, and super capacitors. Scientific arguments to explain the ambiguous behavior in grain boundaries span a wide range of explanations that include the description of phenomena such as interfacial structural disorder, electrostatic phenomena, segregation of impurities and dopants, and even the appearance of glassy pockets. A thermodynamically consistent variational theory is proposed to naturally include the effects of non-diluted segregation, dipolar and self-induced electric field effects, as well as long range, chemically induced (chemo-mechanical) elastic energy density contributions to the total free energy of the system. The developed model provides a rational basis to understand the stability of charge point defect distributions away from the interface and its effect on the charge transport properties of the corresponding polycrystalline chemistries. The theory is demonstrated on GDC, YSZ, and STO and validated against experimentally measured properties.