Structural and phase evolution in mechanically alloyed calcium copper titanate dielectrics

Nanocrystalline calcium-copper-titanate (CCTO) dielectric powders were prepared by mechanical alloying. Phase transformations and structural evolution of the mechanically activated powders were investigated through the Rietveld refinement of the X-ray diffraction results. The crystallite size, lattice strain, and weight fraction of individual phases were estimated based on crystal structure refinement. Furthermore, the microstructural properties and thermal behavior of the milled powders were investigated by Transmission Electron Microscopy (TEM) and Differential Thermal Analysis (DTA), respectively. It was found that CCTO nanocrystals can be successfully synthesized after the amorphization of the initial crystalline materials. Semi-spherical nano-size particles were developed after sufficient milling time. Formation of an amorphous phase during the milling cycle was confirmed by the presence of the glass transition and crystallization peaks in the thermal analysis profiles.