Preparation, Microstructure, and Ferroelectric Properties of Bi3.25La0.75Ti3-xMxO12 (M = Mo, W, Nb, V) Ceramics

A modified citrate-gel method for the preparation of Bi3.25La0.75Ti3-xMxO12 (BLTMx, M = Mo, W, Nb, V) ferroelectric powder and ceramics is presented. The cosubstituent precursors used were ammonium metal citrate aqueous solutions, which were prepared using corresponding metal oxides as starting materials (V2O5, MoO3, and WO3). The intermediate, an amorphous carbonized precursor, was found to directly transform into crystalline Bi4Ti3O12 at a temperature as low as 450 degrees C. The profound effects of cosubstitutions on the texture, microstructure, and ferroelectric properties of the prepared ceramics were studied. The maximal remanent polarization obtained was 15.9, 15.9, 15.3, and 16.3 mu C/cm(2) (10 Hz, 300 kV/cm) for the BLTNb0.03, BLTV0.03, BLTMo0.025, and BLTW0.025 cerarnics, respectively. Dynamic leakage current compensation indicates that no appreciable electric leakage current contributes to the measured hysteresis loops. For BLTW0.025 ceramics, the static leakage current density is below 1.0 mu A/cm(2) within a range of 200 kV/cm. The decrease in +/- P-r after 4.19 x 10(8) cumulative switching cycles is less than 7%.