Structure analysis on the Ba{sub 3}Mg(Ta{sub 1-x}Nb{sub x}){sub 2}O{sub 9} ceramics: Coexistence of order and disorder

Journal Article · Tue Mar 04 00:00:00 EST 2008 · Materials Research Bulletin

DOI:https://doi.org/10.1016/j.materresbull.2007.04.009· OSTI ID:21068219

Janaswamy, Srinivas ^[1]; Murthy, G Sreenivasa; Dias, E D; Murthy, V R.K. ^[2]

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1. WCCR, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009 (United States)
2. Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

The Ba{sub 3}ZnTa{sub 2}O{sub 9} (BZT) and Ba{sub 3}MgTa{sub 2}O{sub 9} (BMT) ceramics, a family of A{sub 3}B{sup 2+}B{sup 5+}{sub 2}O{sub 9} complex perovskites, are extensively utilized in mobile based technologies due to their intrinsic high unloaded quality factor, high dielectric constant and a low (near-zero) resonant frequency temperature coefficient at microwave frequencies. The preparation conditions as well as size and nature of B cations have a profound effect on the final dielectric properties. In this article, we report the effect of Nb{sup 5+} at the Ta{sup 5+} site on the BMT structure prepared at four synthesis temperatures (1300, 1400, 1500 and 1600 deg. C). The analysis has been carried out using the Rietveld technique on the X-ray powder diffraction data. Results suggest that both the preparation temperatures and Nb{sup 5+} content have significant effect on the ordering of B cations in the Ba{sub 3}Mg(Ta{sub 1-x}Nb{sub x}){sub 2}O{sub 9} solid solution. A disordered (cubic) structure is preferred by the 1300 deg. C compounds. The weight percentage of the ordered (trigonal) phase escalates, for a given composition, with increasing calcination temperature. A fully ordered trigonal arrangement exists only for x = 0.0 and 0.2 compounds calcined at 1600 deg. C, and the rest are biphasic (cubic and trigonal). The increase in the cubic fraction upon Nb{sup 5+} augmentation suggests that the solid solution leans more toward the disordered structural arrangement of B{sup 2+} and B{sup 5+} cations.

• OSTI ID: 21068219
• Journal Information: Materials Research Bulletin, Vol. 43, Issue 3; Other Information: DOI: 10.1016/j.materresbull.2007.04.009; PII: S0025-5408(07)00154-7; Copyright (c) 2007 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

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
CALCINATION
CATIONS
CERAMICS
CRYSTAL STRUCTURE
MAGNESIUM COMPOUNDS
MICROWAVE RADIATION
NIOBIUM COMPOUNDS
NIOBIUM IONS
OXIDES
PERMITTIVITY
PEROVSKITES
QUALITY FACTOR
SOLID SOLUTIONS
SYNTHESIS
TANTALUM COMPOUNDS
TANTALUM IONS
TEMPERATURE COEFFICIENT
TEMPERATURE RANGE 1000-4000 K
X-RAY DIFFRACTION