Sol–gel synthesis, structural and dielectric properties of Y-doped BaTiO₃ ceramics

Prepared nano-polycrystalline of BaTiO₃ containing 20, 40, 60 and 80 mol.% Y were prepared by sol–gel method. Consider BaTiO₃ perovskite structure where Ba atom is replaced by amounts Y. Careful X-ray diffraction analysis showed the presence of tetragonal phase. The effect of the Y³⁺ content in BaTiO₃ ceramics materials was investigated. The incorporation of yttrium into BaTiO₃ unit cell was smoothly alternated the bond vibration of the crystal lattice. By using the Raman-active modes, it was observed that the tetragonal phase is present in all synthesized samples. The morphology of obtaining ceramics is found to be nanosized. Y-doped BaTiO₃ ceramics exhibit high values of dielectric constants and low dielectric losses, such properties, combined with the microstructural development arising from the influence of sintering temperature. The fitting derived from the Curie-Wiess laws, confirm that all samples are normal ferroelectric with first order transition accompanied by displacive ones. The increase of conductivity is linked to the formation of oxygen vacancies arise from the dissociation of molecules during the synthesis process.