Microstructure and texture dependence of the dielectric anomalies and dc conductivity of Bi3TiNbO9 ferroelectric ceramics

11 pages, 16 figures, 1 table.-- PACS: 81.05.Je; 77.84.Dy; 81.40.Ef; 77.22.Ch; 77.22.Gm; 77.80.Bh; 72.80.Sk; 81.20.Ev; 61.50.Nw; 77.22.EjCeramics of composition Bi3TiNbO9 (BTN) and perovskite-layered structure (Aurivillius type) [B. Aurivillius, Ark. Kemi 1, 463 (1949)] were processed by natural sintering and hot pressing from amorphous precursors. Precursors were obtained by mechanochemical activation of stoichiometric mixtures of oxides. These materials are in general interesting for their use as high-temperature piezoelectrics. Among them, BTN possesses the highest ferroparaelectric phase-transition temperature (>900 °C). The transition temperature establishes the working limit of the ceramic and the electric properties, especially the dc conductivity, affect on its polarizability. In this work, dielectric studies of BTN ceramics with controlled texture and microstructure have been made at 1, 100 KHz, and 1 MHZ and in the temperature range from 200 °C up to the ferroparaelectric transition temperature. Values of ~250 at 200 °C are achieved in ceramics hot pressed at temperatures as low as 700 °C for 1 h.The authors thank the research projects 07N/0076/2002 of Spanish CAM and MAT2001-0561 of Spanish MCyT for the financial support of this work.Peer reviewe