Structural, ferroelectric, and dielectric properties of vanadium-doped Bi4-x/3Ti3-xVxO12

The microstructure, ferroelectric, and dielectric properties of vanadium-doped Bi4Ti3O12 ceramics have been investigated. V substitution is found to cause a transition from an orthorhombic phase to a tetragonal phase at x similar to 0.03, and again to an orthorhombic phase at higher V content. The ferroelectric properties of Bi4Ti3O12 were significantly improved by V doping. The 2P(r) of Bi4Ti3O12 is 16 mu C/cm(2), and it reaches a maximum value of 26.4 mu C/cm(2) when the V content is 0.03. The two relaxation peaks (P-I, P-II) are observed in the dielectric loss (D) curves for all of the samples. The P-I and P-II peaks related to oxygen vacancies tend to decrease with V doping, which implies the decreasing of the oxygen vacancy concentration caused by V doping and favors the improvement of 2P(r) and 2E(c). On the contrary, Raman spectra reveal the occurrence of Ti vacancies when V content is more than x=0.01, which may be responsible for the variation of the microstructure and the deterioration of 2P(r) and 2E(c). The ferroelectricity of V doping Bi4-x/3Ti3-xVxO12 ceramics is therefore likely dominated by these two competing mechanisms, with the optimal ferroelectric properties appearing at V content x=0.03. (c) 2006 American Institute of Physics.