Dielectric properties and phase transition in SrBi2Nb2O9-SrBi2Ta2O9 solid solution

Structural and dielectric properties of SrBi2(Nb1-xTx)(2)O-9 solid solution, (SBNT), with x = 0.0, 0.1, 0.2, 0.3, 0.5, 0.7, 1.0 were investigated. Crystal structure at room temperature was analyzed by X-ray diffraction study. SBNT exhibits an Aurivillius structure and the c lattice constant decreases with increasing concentration of Ta in the solution. The studies of real (epsilon') and imaginary (epsilon '') parts of permittivity as a function of temperature (20-500 degrees C) and frequency (0.1-100 kHz) were carried out, as well. The anomalies of epsilon'(T) and epsilon ''(T) associated with phase transition from the tetragonal paraelectric phase (PT) to the orthorhombic ferroelectric phase (F-O) were observed. They are strongly dependent on the Ta content in the solution. The grain structure and chemical composition were examined by a scanning electron microscope (SEM), with an energy dispersion spectrometer (EDS). The EDS analysis indicated a homogeneous distribution of all elements of ceramics within the grains. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.