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Title: The local crystal chemistry and dielectric properties of the cubic pyrochlore phase in the Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M {sup 2+}=Ni{sup 2+} and Mg{sup 2+}) systems

Abstract

The composition, dielectric properties and inherent displacive disorder of a Bi-based, misplaced-displacive cubic pyrochlore phase found in two ternary Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M=Ni and Mg) systems has been investigated. The dielectric permittivities (up to 1 MHz) of (Bi{sub 0.825}Ni{sub 0.125}{open_square}{sub 0.05}){sub 2}(Ni{sub 0.25}Nb{sub 0.75}){sub 2}O{sub 7} and (Bi{sub 0.835}Mg{sub 0.085}{open_square}{sub 0.08}){sub 2}(Mg{sub 0.235}Nb{sub 0.765}){sub 2}O{sub 7} at room temperature are found to be 116 and 151, respectively, while the dielectric loss tangents are 0.00065 and 0.00042, respectively, at 100 kHz. A highly structured characteristic diffuse intensity distribution apparent in electron diffraction is reported in both cases and partially interpreted in terms of large amplitude, {beta}-cristobalite-type tetrahedral rotations of the O'A {sub 2} tetrahedral framework sub-structure of the ideal pyrochlore structure type. Bond valence sum calculations are used to investigate the local crystal chemistry responsible for this displacive disorder. - Graphical abstract: The characteristic {beta}-cristobalite-type displacive disorder of the O'A {sub 2} sub-structure (of the ideal pyrochlore structure type) drawn relative to the surrounding B {sub 2}O{sub 6} octahedral framework sub-structure and responsible for the observed structured diffuse intensity distribution in the Bi{sub 1.65}Ni{sub 0.75}Nb{sub 1.50}O{sub 7} and Bi{sub 1.67}Mg{sub 0.64}Nb{sub 1.53}O{sub 7} misplaced-displacive cubicmore » pyrochlores.« less

Authors:
 [1];  [1];  [2]
  1. Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia)
  2. Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia), E-mail: withers@rsc.anu.edu.au
Publication Date:
OSTI Identifier:
21015682
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 2; Other Information: DOI: 10.1016/j.jssc.2006.10.039; PII: S0022-4596(06)00571-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BISMUTH OXIDES; CRISTOBALITE; CUBIC LATTICES; DIELECTRIC MATERIALS; DISTRIBUTION; ELECTRON DIFFRACTION; KHZ RANGE 100-1000; MAGNESIUM IONS; MHZ RANGE; NICKEL IONS; NIOBIUM OXIDES; PERMITTIVITY; PYROCHLORE; TEMPERATURE RANGE 0273-0400 K

Citation Formats

Nguyen, Binh, Liu Yun, and Withers, Ray L. The local crystal chemistry and dielectric properties of the cubic pyrochlore phase in the Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M {sup 2+}=Ni{sup 2+} and Mg{sup 2+}) systems. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.10.039.
Nguyen, Binh, Liu Yun, & Withers, Ray L. The local crystal chemistry and dielectric properties of the cubic pyrochlore phase in the Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M {sup 2+}=Ni{sup 2+} and Mg{sup 2+}) systems. United States. doi:10.1016/j.jssc.2006.10.039.
Nguyen, Binh, Liu Yun, and Withers, Ray L. Thu . "The local crystal chemistry and dielectric properties of the cubic pyrochlore phase in the Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M {sup 2+}=Ni{sup 2+} and Mg{sup 2+}) systems". United States. doi:10.1016/j.jssc.2006.10.039.
@article{osti_21015682,
title = {The local crystal chemistry and dielectric properties of the cubic pyrochlore phase in the Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M {sup 2+}=Ni{sup 2+} and Mg{sup 2+}) systems},
author = {Nguyen, Binh and Liu Yun and Withers, Ray L.},
abstractNote = {The composition, dielectric properties and inherent displacive disorder of a Bi-based, misplaced-displacive cubic pyrochlore phase found in two ternary Bi{sub 2}O{sub 3} - M {sup 2+}O-Nb{sub 2}O{sub 5} (M=Ni and Mg) systems has been investigated. The dielectric permittivities (up to 1 MHz) of (Bi{sub 0.825}Ni{sub 0.125}{open_square}{sub 0.05}){sub 2}(Ni{sub 0.25}Nb{sub 0.75}){sub 2}O{sub 7} and (Bi{sub 0.835}Mg{sub 0.085}{open_square}{sub 0.08}){sub 2}(Mg{sub 0.235}Nb{sub 0.765}){sub 2}O{sub 7} at room temperature are found to be 116 and 151, respectively, while the dielectric loss tangents are 0.00065 and 0.00042, respectively, at 100 kHz. A highly structured characteristic diffuse intensity distribution apparent in electron diffraction is reported in both cases and partially interpreted in terms of large amplitude, {beta}-cristobalite-type tetrahedral rotations of the O'A {sub 2} tetrahedral framework sub-structure of the ideal pyrochlore structure type. Bond valence sum calculations are used to investigate the local crystal chemistry responsible for this displacive disorder. - Graphical abstract: The characteristic {beta}-cristobalite-type displacive disorder of the O'A {sub 2} sub-structure (of the ideal pyrochlore structure type) drawn relative to the surrounding B {sub 2}O{sub 6} octahedral framework sub-structure and responsible for the observed structured diffuse intensity distribution in the Bi{sub 1.65}Ni{sub 0.75}Nb{sub 1.50}O{sub 7} and Bi{sub 1.67}Mg{sub 0.64}Nb{sub 1.53}O{sub 7} misplaced-displacive cubic pyrochlores.},
doi = {10.1016/j.jssc.2006.10.039},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 180,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}