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Relaxor characteristics of layered Ba1-(3/2)xLaxBi2Nb2O9 ceramics

Karthik, C and Varma, KBR and Maglione, Mario and Etourneau, J (2007) Relaxor characteristics of layered Ba1-(3/2)xLaxBi2Nb2O9 ceramics. In: Journal of Applied Physics, 101 (1). 014106 -014106.

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Barium lanthanum bismuth niobate Ba1−(3/2)xLaxBi2Nb2O9 (x = 0, 0.05, 0.1, and 0.15) powders have been prepared via solid state reaction route. The monophasic layered perovskite nature of each composition of these was confirmed by x-ray diffraction studies. A continuous decrease in the lattice parameter c of parent BaBi2Nb2O9 with increase in La3+ doping level was noteworthy. A decrease in dielectric constant maximum (εm), a shift in dielectric anomaly to lower temperatures (from 488 to 382 K), and an increase in the diffuseness (γ) (from 1.58 to 1.84) of dielectric anomaly were encountered on increasing x from 0 to 0.15. Vogel-Fulcher analyses showed a decrease in freezing temperature (Tf) (from 157 to 40 K) and an increase in the activation energy (0.53 to 1.12 eV) for frequency dispersion with increase in La3+ content. A downward shift in the peak position of the pyroelectric coefficient with increasing La3+ doping level was observed. The observed changes in the above physical properties were attributed to the increase in A-site chemical heterogeneity as a result of aliovalent La3+ doping on Ba2+ sites and associated A-site vacancy formation.

Item Type: Journal Article
Publication: Journal of Applied Physics
Publisher: American Institute of Physics
Additional Information: Copyright of this article belongs to American Institute of Physics.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 05 Jan 2012 09:51
Last Modified: 05 Jan 2012 09:51
URI: http://eprints.iisc.ac.in/id/eprint/43027

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