Dielectric Properties of Cerium Doped Barium Titanate

Barium titanate (BaTiO3) is a ferroelectric material has become one of the most important electroceramic materials due to its dielectric, ferroelectric and piezoelectric properties. Ferroelectric properties and a high... [ view full abstract ]

Barium titanate (BaTiO₃) is a ferroelectric material has become one of the most important electroceramic materials due to its dielectric, ferroelectric and piezoelectric properties. Ferroelectric properties and a high dielectric constant make BaTiO₃ useful in an array of applications such as multilayer ceramic capacitors, gate dielectrics, waveguide modulators, IR detectors. This study is devoted to the investigation of dielectric spectroscopy of BaTiO₃ doped with different concentration of cerium ions. The ferroelectricity of BaTiO₃ originates from the uniform direction of Ti–O dipoles. Rare-earth oxide, which has intermediate ionic radius between Ba²⁺ and Ti⁴⁺ ions, is an important additive in BaTiO₃-based ceramics to modification dielectric properties, due to its substitution on Ba-site or Ti-site or both. The cerium ion can enter into the BaTiO₃ lattice in two oxidation states, as Ce³⁺ or Ce⁴⁺ into Ba- or Ti-sites respectively. Ceramic samples of doped BaTiO₃ were prepared by solid-state reaction in order to promote the incorporation of Ce ions into Ti-sites. As the ionic radius of Ce⁴⁺ is large than radius of Ti⁴⁺ then the movement of the center Ti⁴⁺ ion becomes difficult. Consequently, the ferroelectric properties of local doped BaTiO3 is significantly weakened with the substitution doping Ce ions. This study shows that the increase of Cerium dopants in the Ti-site of BaTiO₃ lattice diminishes ferroelectric order and the relaxor behaviour is enhanced. The investigation was carried in a broad temperature (140 – 500 K) and frequency range (5 mHz – 50 GHz). The evolution of temperature and frequency dependences of dielectric permittivity will be discussed in this paper.