Polarization contributions to DC bias characteristics of nanograined BaTiO<sub>3</sub>-based ceramics
Takashi Teranishi, Ruku Ozaki, Shinya Kondo, Akira Kishimoto
Abstract
Abstract The domain configuration contributions to the DC bias characteristics of nanograined BaTiO 3 were clarified. Domain boundaries became more ambiguous with decreasing grain size ( g.s. ), whereas domain patterns partially vanished because of the reduction in BT ferroelectricity, in the g.s. range <1 μ m. Additionally, intergranular stress increased with decreasing g.s. , resulting in crystal lattice hardening in the vicinity of the domain walls (DWs) and suppression of dipole fluctuations in the DWs. These domain structural variations with the domain size ( d.s. ) reduced permittivity in the absence of a DC electric field, resulting in improvements in permittivity depressions in an electric field (Δ ε ). Magnesium substitution slightly decreased the d.s . The increase in DW density upon Mg loading implied defect pairs, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">Mg</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">Ti</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>"</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> – <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">V</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">o</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>•</mml:mi> <mml:mi>•</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>,</mml:mo> </mml:math> which acted as new DW pinning centers, thereby subdividing the DWs. The Δ ε notably improved via Mg loading, because a defect pair effectively pins the DWs under the electric field.