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PUBLICATIONS

Phase Formation, Crystal Chemistry, and Properties in the Magnetic Dielectric System Bi2O3-Fe2O3-Nb2O5

Published

Author(s)

M W. Lufaso, Terrell A. Vanderah, I M. Pazos, Igor Levin, Juan C. Nino, Virgil Provenzano, Peter K. Schenck, Robert S. Roth

Abstract

Subsolidus phase relations have been determined for the Bi2O3-Fe2O3-Nb2O5 system in air (900-1075 C). Three new ternary phases were observed Bi3Fe0.5Nb1.5O9 with an Aurivillius-type structure, and two phases with approximate stoichiometries Bi17Fe2Nb31O106 and Bi17Fe3Nb30O105 that appear to be structurally related to Bi8Nb18O57. The fourth ternary phase found in this system is pyrochlore. X-ray powder diffraction data confirmed that all Bi-Fe-Nb-O pyrochlores form with displacively disordered A2O networks. A structural refinement of the pyrochlore 0.4400:0.2700:0.2900 Bi2O3:Fe2O3:Nb2O5 using neutron powder diffraction data is reported. Bi-Fe-Nb-O pyrochlores exhibited overall paramagnetic behavior with large negative Curie-Weiss temperature intercepts, slight superparamagnetic effects, and depressed observed moments compared to high-spin, spin-only values. The single-phase pyrochlore with composition Bi1.657Fe1.092Nb1.150O7 exhibited low-temperature dielectric relaxation similar to that observed for Bi1.5Zn0.92Nb1.5O6.92; at 1 MHz and 200 K the relative permittivity was 125. Bi-Fe-Nb-O pyrochlores were readily obtained as single crystals and also as textured thin films used pulsed laser deposition.
Citation
Journal of Solid State Chemistry
Volume
179
Issue
12
Pub Type
Journals

Keywords

Bi2O3-Fe2O3-Nb2O5, phase diagram, phase equilibria
Materials and Ceramics

Citation

Lufaso, M. , Vanderah, T. , Pazos, I. , Levin, I. , Nino, J. , Provenzano, V. , Schenck, P. and Roth, R. (2006), Phase Formation, Crystal Chemistry, and Properties in the Magnetic Dielectric System Bi<sub>2</sub>O<sub>3-</sub>Fe<sub>2</sub>O<sub>3-</sub>Nb<sub>2</sub>O<sub>5</sub>, Journal of Solid State Chemistry (Accessed December 26, 2024)

Issues

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Created June 21, 2006, Updated October 12, 2021