Structure and dielectric properties of Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} tungsten bronze ceramics
- College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19(A) Yu Quan Road, Beijing 100049 (China)
- Beijing National Day School, 66 Yu Quan Road, Beijing 100039 (China)
Highlights: ► Tetragonal tungsten bronze ceramic Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} was prepared. ► Titanium was replaced by copper in M{sub 5}RTi{sub 3}Nb{sub 7}O{sub 30} for the first time. ► Detailed structural information was retrieved by Rietveld refinement. ► An obvious relaxor-like dielectric behavior was observed in this ceramic, ion disorders in A1 and B sites contribute to this behavior. - Abstract: A new type of tungsten bronze ceramic Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} has been prepared by a conventional solid-state reaction technique. Its structural, dielectric properties were investigated. Rietveld analysis shows that Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} has a single-phase tetragonal (space group P4bm and lattice constants a = b = 12.4961(4) Å, c = 3.9426(8) Å, V = 615.66(4) Å{sup 3}) tungsten bronze structure. The occupations of sites A and B are quite interesting. A1 sites are fully disordered occupied by Ba ions and Nd ions and A2 sites for Ba ions only, while B-sites are equal for both Cu and Nb ions to occupy. This material exhibits an obvious relaxation behavior in the 213–573 K temperature range. The dielectric constants have been fitted by the modified Curie–Weiss law and all the estimated γ values are close to 2, confirming the typical relaxor ferroelectric behavior. The disorders of Ba{sup 2+} or Nd{sup 3+} in A1 sites and Nb{sup 5+}, Cu{sup 2+} in B sites induced by the oxygen vacancies may contribute to this dielectric behavior.
- OSTI ID:
- 22290437
- Journal Information:
- Materials Research Bulletin, Vol. 48, Issue 5; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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