Diffusion Induced Grain-Boundary Migration and Enhanced Grain Growth in BaTiO3

다국어 초록 (Multilingual Abstract)

The effect of diffusion induced grain-boundary migration (DIGM) on grain growth has been studied in a model system of BaTiO_(3)-PbTiO_(3). When sintered BaTiO_(3) samples of two different grain sizes were heat-treated in contact with PbTiO_(3), DIGM occurred in the coarse-grained samples (∼200㎛ in average size) while fast grain growth was observed in the fine-grained samples (∼4㎛). Energy dispersive spectroscopy (EDS) analysis confirmed that the fast growth of BaTiO_(3) grains was accompanied by the alloying of Pb and thus related to DIGM. A calculation of coherency strain energy for the BaTiO_(3)-PbTiO_(3) system showed that the coherency strain energy of a coherent (Ba_(0.8)Pb_(0.2))TiO_(3) layer on BaTiO_(3) was between 2 and 3 MJ/㎥ depending on the surface orientation. The calculated coherency strain energy values are much higher than the capillary energy due to the grain boundary curvature of 4㎛ grains in the fine-grained sample. The observed enhancement of grain growth appears therefore to be a result of DIGM. Such grain growth enhancement by DIGM is thought to occur in materials processing under chemical inhomogeneity or inequilibrium, for example, in the sintering of powder mixtures and in the annealing of chemically inhomogeneous polycrystals.

목차 (Table of Contents)

• 1. Introduction
• 2. Experimental Procedure
• 3. Experimental Results and Discussion
• 3.1. Heat-treatment of Coarse-grained BaTiO_(3)Samples with PbTiO_(3)
• 3.2. Heat-treatment of Fine-grained BaTiO_(3)Samples with PbTiO_(3)
• 3.3. Coherency Strain Energy in the BaTiO_(3)-PbTiO_(3)System
• 3.4. Driving Force for Grain Growth During Solute Diffusion Along Grain Boundaries
• 4. Conclusion
• Acknowledgment
• References