Abstract
Polycrystalline powder samples of SrBi2-xPbxNb 2O9-x/2 (x = 0, 0.25, 0.5, 1, 1.5 and 2) were prepared via the conventional solid state reaction route. X-ray powder diffraction studies carried out on the powdered samples confirmed the possibility of completely replacing Bi3+ by Pb2+ without altering its basic layered structure. Transmission Electron Microscopy (TEM) associated with Selected Area Electron Diffraction (SAED) studies established the presence of superlattice refections linked with octahedral tilting. Interestingly, the superlattice reflections in the electron diffraction pattern gradually disappear with increase in lead content in SrBi2Nb2O9. The dielectric properties that were studied in the 100 Hz to 10 MHz and room temperature to 600° C range confirmed the Tc (ferroelectric to paraelectric transition temperature) to be lead content dependent. However, there was no clear well defined ferroelectric to paraelectric transition observed for the compositions corresponding to x≥1. The increase in dielectric constant (εr) with the increase in lead content at all the frequencies and temperatures under study was attributed to an increase in intrinsic polarization arising from cationic size effect.
Original language | English |
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Pages (from-to) | 113-119 |
Number of pages | 7 |
Journal | Ferroelectrics |
Volume | 324 |
DOIs | |
State | Published - 2005 |
Externally published | Yes |
Keywords
- Aurivillius oxide
- Electron diffraction
- Lead doping
- Octahedral tilting