Polymorphism and dielectric properties of Sc-doped BaTiO3 nanopowders synthesized by sol–gel method

Sc-doped barium titanate (BaTiO3) nanopowders and ceramics were prepared by a sol–gel method for the first time. The polymorphism, microstructure and dielectric properties were investigated. Pseudo-cubic Sc-doped BaTiO3 nanopowders with a particle size of 30–40 nm have been achieved at low temperature of 800 °C. A phase diagram for the solid solution system BaTi1−xScxO3−δ was obtained. The limit of pseudo-cubic Sc-doped BaTiO3 solid solution (BTss) and the stable hexagonal phase have a large dependence on temperatures. The dopant of Sc3+ can also dramatically refine the grain size of BaTiO3 to 300 nm when x = 0.10. For different Sc3+ content in BaTiO3 ceramics, two types of impedance response appeared, and the resistivity of ceramics was dominated by bulk resistance or grain boundary resistance. Curie temperature (TC) and dielectric constant decreased by increasing the Sc3+ content. Relaxor behaviour occurs below room temperature when x = 0.10.

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► Sc-doped BaTiO3 nanopowders were prepared by a sol–gel method for the first time.
► Doping with Sc3+ can dramatically refine the grain size of BaTiO3 ceramics.
► Two types of impedance response appeared in Sc-doped BaTiO3 ceramics.
► Curie temperature and dielectric constant decreased with increasing Sc3+ content.
► A relaxor behaviour occurs below room temperature for high doping content of Sc3+.