Final Report Summary - EEEF-GBE-CNS (Effect of an External Electric Field on Grain Boundary Evolution in the Course of Nano-Ceramic Sintering) Consolidation of oxides nanoparticles in the presences of electric field show promising results for retaining the nanostructure in the bulk. Although the sintering of nanoparticles shares the same basic principles as those for the sintering of coarser particles, a number of issues and challenges are specific to nanosintering. From thermodynamic point of view, solid state sintering can be described as a thermally activated process during which the total interfacial free energy of an assembly of particles of equilibrium chemical composition decreases. Moreover, the consolidation and the grain growth pattern can be determined by ratio between the solid-vapour interfacial energy to solid-solid interfacial (i.e. grain boundary) energy of the material .We propose to take a first step towards unraveling these processes in the presence of external electric field by testing the synergistic effects of external electric field and dopants on the grain boundary energy and sintering mechanism of oxides nanoceramics. The main objective of this project is to study the individual contribution of dopant on the surface and interfacial energies. To accomplish this objective we have developed experimental setup for measuring these energies during the consultation process. We hypothesize that the use of dopant will show significant effect on these energies and by that will change the sintering course. Our second objective was to identify and study the effect of a DC electric field on the dopants, the interfacial and surface energies, the space charge layer, and the grain size of the materials. We mapped the contribution of each parameter to the consolidation process.In the first stage of the project two type of nano oxides, lithium doped and undoped magnesium aluminate spinel and neodymium doped ceria were synthesized and fully characterized. Than the effect of dopant level and applied DC electric field on the consolidation and energetics of the synthesized materials was investigated. 9 peer reviewed publications have been published so far, and about 4 manuscripts are planned or in preparation; 36 lectures, often at prestigious international events, and many more posters and other dissemination actions have been presented. In conclusion the project has produced a some novel scientific knowledge and scientific breakthroughs in the understanding of the effect of electric filed on sintering of nano oxides. Application of those findings can have dramatic positive impacts on future developments of new sintering routes.
