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Structural and Dielectric Properties of $SrBi_{2-x}Pb_{x}Nb_{2}O_{9-x/2}(0 \leq x \leq 2)$

Karthik, C and Ravishankar, N and Varma, KBR (2005) Structural and Dielectric Properties of $SrBi_{2-x}Pb_{x}Nb_{2}O_{9-x/2}(0 \leq x \leq 2)$. In: Ferroelectrics, 324 . pp. 113-119.

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Polycrystalline powder samples of $SrBi_{2-x}Pb_{x}Nb_{2}O_{9-x}2$ (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 $Bi^{3+}$ by $Pb^{2+}$ without altering its basic layered structure. Transmission Electron Microscopy (TEM) associated with Selected Area Electron Diffraction (SAED) studies established the presence of superlattice reflections linked with octahedral tilting. Interestingly, the superlattice reflections in the electron diffraction pattern gradually disappear with increase in lead content in $SrBi_{2}Nb_{2}O_{9}$. The dielectric properties that were studied in the 100 Hz to 10 MHz and room temperature to 600 degrees C range confirmed the $T_{c}$ (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 \geq 1. The increase in dielectric constant $(\epsilon_{r})$ 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.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Taylor and Francis Ltd.
Keywords: Aurivillius oxide; lead doping; electron diffraction; octahedral tilting
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Depositing User: B.S Priyanka
Date Deposited: 19 Jan 2006
Last Modified: 27 Aug 2008 11:41
URI: http://eprints.iisc.ac.in/id/eprint/5159

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