Synthesis, Structure, and Properties of Bi3.25Pr0.75Ti2.97V0.03O12 Ferroelectric Ceramics

Praseodymium and vanadium cosubstituted Bi 4 Ti 3 O 12 was synthesized using a modified citrate-gel method. The crystallization was promoted by the oxidation of residual carbon produced by decomposition of −CH x groups resulting in a crystallization temperature as low as 450 °C. The as-synthesized powder consisted of uniform spherical particles with a mean size of 57 nm and a standard deviation of 14 nm. The ceramic prepared from the as-synthesized powder at 900 °C consisted mainly of randomly arranged platelets with a thickness of 200 nm. The Rietveld refinement in the orthorhombic space group Aba 2 for the as-prepared Pr 3+ and V 5+ cosubstituted Bi 4 Ti 3 O 12 resulted in a convergent refinement ( R wp = 5.01%). The remanent polarization (2 P r ) and coercive field (2 E c ) values measured at room temperature with a maximum electric field of ±300 kV/cm were 35 μC/cm 2 and 148 kV/cm, respectively. The ceramic has a very low ohmic conductivity, and the leakage current density is below 1 μA/cm 2 up to 200 kV/cm. No profound fatigue was observed after switching over 10 8 cycles. The evolution of 2 E c, 2 P r, P max (maximum polarization), and P max / P r with E max (maximum electric field) is discussed using an ideal and a four components ferroelectric capacitor model. The observed linear relationship between P max / P r and E max provides the possibility to calculate the field independent dielectric constant (282) and nonremanent polarization (2.7 μC/cm 2 at E max = 300 kV/cm) for the ceramic studied.