Aliovalent B-Site Modification On Three- And Four-Layer Aurivillius Intergrowth

Electrical properties of Nb-, V-, and W-doped Bi4Ti3O12-MBi4Ti4O15 (BIT-MBTi) (M=Ca,Sr) compounds were investigated. The remanent polarization (2P(r)) and piezoelectric coefficient (d(33)) Of BIT-MBTi are greatly increased by such donor doping. W-doped and Nb-doped BIT-SBTi exhibited the greatest enlargement in 2P(r) and d(33), respectively. Nb doping also increases 2P(r) and d(33) of BIT-CBTi though not that much as in the BIT-SBTi case. BIT-CBTi thin film shows a high 2P(r) value of 39 mu C/cm(2). The enhanced properties are thought to stem from the reduced concentration and weakened mobility of oxygen vacancies. Increased activation energy of conduction further confirmed the restraint of oxygen vacancies. The different optimal V-doping content for 2P(r) and d(33) in BIT-SBTi might be related to the fact that V doping could affect the structure and density of domain more apparently than the concentration of oxygen vacancies. The thermal variation of dielectric constant of BIT-CBTi shows a distinctive double anomaly at 658 and 728 degrees C. The first dielectric anomaly is related to the regulation of BIT parts, and the second one corresponds to the ferroelectric-paraelectric phase transition. (C) 2008 American Institute of Physics.