Study of dielectric properties of nanocrystalline material BaTiO₃-SiO₂

Abstract

Within the temperature range of −50–200 °C the dielectric properties of nanocrystalline samples of BaTiO₃ and BaTiO₃-SiO₂ (1 wt % SiO₂) were studied at frequencies of 25 Hz–1 MHz. The addition of 1 wt % SiO₂ to the BaTiO₃ leads to a noticeable decrease in the dielectric permittivity of the material and a slight decrease in the temperatures of the ferroelectric phase transition and the transition from the orthorhombic toward tetragonal phase. It is shown that the BaTiO₃-SiO₂ sample exhibits some features of a relaxor ferroelectric. It is revealed that a significant contribution to the ac conductivity in the ferroelectric phase of BaTiO₃ - SiO₂ comes from the domain and interphase boundaries dynamics. Above TC, the hopping mechanism of conduction dominates.

Keywords:

• BaTiO₃ and BaTiO₃-SiO₂ nanoceramics
• dielectric permittivity
• relaxor-like behavior
• Vogel-Fulcher relation
• electrical conductivity