# Crystal Chemistry of a New Solid Solution in the $BaO-Bi_2O_3-Nb_2O_5$ System: $Ba_{5x/2}Bi_{(1-x)5/3}Nb_5O_{15}$

Muktha, B and Simon, A and Darriet, J and Row, Guru TN (2006) Crystal Chemistry of a New Solid Solution in the $BaO-Bi_2O_3-Nb_2O_5$ System: $Ba_{5x/2}Bi_{(1-x)5/3}Nb_5O_{15}$. In: Chemistry of Materials, 18 (5). 1240 -1246.

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## Abstract

A solid solution of the type $Ba_{5x/2}Bi_{(1-x)5/3}Nb_5O_{15}$ has been identified in the $BaO-Bi_2O_3-Nb_2O_5$ system for the first time. The limits of the solid solution are within the range $0.52\leq x \leq0.80$. The compositions x = 0.52, 0.60, 0.72, 0.77, 0.78, and 0.80 were synthesized by the solid-state technique from the starting materials in stoichiometric quantities. The powder X-ray patterns of all the phases in the domain indicate a structural similarity to tetragonal tungsten bronzes (TTBs). The compositions below x = 0.52 and those above x = 0.80 exhibit barium niobate and bismuth niobate impurities, respectively. Single crystals of the composition x = 0.77 were obtained by the melt cooling technique. The crystal structure of $Ba_{3.85/2}Bi_{1.15/3}Nb_5O_{15}$ (x = 0.77) was solved in the tetragonal space group P4bm (No. 100) with a = 12.4938 (14) Å, c = 3.9519 (2) Å, V = 616.87 (10) $\AA^3$, and Z = 2 and was refined to an R index of 0.034. Dielectric measurements on all the phases indicate a typical relaxor behavior with a broad phase transition at $T_m\approx300 K$.

Item Type: Journal Article Copyright of this article belongs to American Chemical Society. Division of Chemical Sciences > Solid State & Structural Chemistry Unit 02 Jun 2006 19 Sep 2010 04:28 http://eprints.iisc.ernet.in/id/eprint/7302