Characterization of Solid‐State Reaction of Barium Carbonate and Titanium Dioxide by Spatially Resolved Electron Energy Loss Spectroscopy

A mixture of ultrafine submicrometer-sized BaCO3 powder and TiO2 (rutile) powder was calcined in air at 700°C, 800°C, and 900°C, and then quenched to liquid nitrogen temperature in each case. The cross-sectional quenched specimens were characterized by spatially resolved electron energy-loss spectroscopy (SR-EELS). The energy-loss near-edge structures (ELNES) were sequentially extracted at 1.3 to 5.3 nm in width from SR-EELS image obtained from the rectangularly cut SR-EELS slit aperture put on the synthesized BaTiO3 layer and TiO2 rutile powder. The ELNES of Ti-L2,3 edges and Ba-M4,5 edges clearly show fine structure changes from the surface of BaTiO3 layer to the TiO2 bulk region reflected from crystallinity of synthesized BaTiO3, lattice distortion of TiO2 caused by Ba diffusion, and lattice misfit between BaTiO3 and TiO2 without formation of Ba2TiO4 and other titanate phases.