X-ray structure analysis of BaMg1/3(Ta,Nbx)2/3O3 ceramics revealed that BaMg1/3Ta2/3O3 (BMT) has an ordered trigonal phase as well as a disordered cubic phase depending on the preparation temperature. Complete ordered phase for BaMg1/3Nb2/3O3 (BMN) has not been observed. The ordering of Mg, Ta and Nb cations has dependence on the size, charge difference and calcination temperature. © 2002 Elsevier Science B.V. All rights reserved.

G. Sreenivasa Murthy

E. D. Dias

Vemuri Rama Krishna Murthy

BARIUM COMPOUNDS

Calcination

CRYSTAL RESONATORS

Crystal Structure

High temperature effects

Perovskite

Polycrystalline materials

Positive ions

X ray analysis

DISORDERED CUBIC PHASES

Ceramic materials

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IIT Madras

Structural analysis of BaMg1/3(Ta,Nb)2/3O3 ceramics

Materials Letters

The dependence of the microwave dielectric properties of xBa3MgNb2O9–(1-x)Ba2InNbO6 [x = 0.4, 0.6, 0.8] on the structural parameters is investigated. The solid-state reaction technique is applied to synthesize these materials and the structural parameters are obtained from the Rietveld refinement of the X-ray diffraction (XRD) data of the samples. The Rietveld refinement confirms the tetragonal crystal structure of all the samples with space group P4/mnc (D4h6). It has been observed that the Raman shift of the stretching mode ν1 (BO6) and the ionic polarizability of the cations strongly influenced the dielectric constant (εr) whereas the value of the quality factor Qf depends upon the width of ν1 (BO6) mode. It is observed that the temperature coefficient of resonant frequency (τf) increases with the increase of the octahedral-distortion in the crystal structure. The factors affecting the microwave dielectric properties are discussed based on the vibrational and structural data. © 2017 Elsevier Ltd

Materials Research Bulletin

Crystal structure, Raman spectroscopy and microwave dielectric properties of xBa3MgNb2O9–(1-x)Ba2InNbO6 [x = 0.4, 0.6, 0.8]

The Ba3ZnTa2O9 (BZT) and Ba3MgTa2O9 (BMT) ceramics, a family of A3B2+B5+2O9 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 Nb5+ at the Ta5+ site on the BMT structure prepared at four synthesis temperatures (1300, 1400, 1500 and 1600 °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 Nb5+ content have significant effect on the ordering of B cations in the Ba3Mg(Ta1-xNbx)2O9 solid solution. A disordered (cubic) structure is preferred by the 1300 °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 °C, and the rest are biphasic (cubic and trigonal). The increase in the cubic fraction upon Nb5+ augmentation suggests that the solid solution leans more toward the disordered structural arrangement of B2+ and B5+ cations. © 2007 Elsevier Ltd. All rights reserved.

Structure analysis on the Ba3Mg(Ta1-xNbx)2O9 ceramics: Coexistence of order and disorder

Structure analysis of polycrystalline BaMg1/3Ta 1/3Nb1/3O3 ceramics has been carried out using the Rietveld technique, wherein the B cations (Mg, Ta, and Nb) have the same occupancy with a size difference and charge imbalance. The compound has an ordered trigonal structure as well as a disordered cubic phase depending on the preparation temperature. The weight percentage of the ordered phase is found to increase with a rise in the calcination temperature. © Pleiades Publishing, Inc., 2006.

Crystallography Reports

Ordering in BaMg1/3Ta1/3Nb1/3O3 ceramics: An X-ray Rietveld analysis

Journal of the American Ceramic Society

Dielectric nonlinear behavior of (Ba0.95Ca0.05)(Ti0.83Zr0.17)O3-based multi-layer ceramic capacitor

Improved High-Q Dielectric Resonator with Complex Perovskite Structure

Journal of Materials Research

Ordering and microwave dielectric properties of Ba(Ni1/3Nb2/3)O3 ceramics

Journal of Materials Science

10.1023/a:1018574505601

Microelectronic Engineering

Interferometric study of piezoelectric degradation in ferroelectric thin films

Journal	Materials Letters
ISSN	0167577X
Open Access	No