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.

G. Sreenivasa Murthy

E. D. Dias

Vemuri Rama Krishna Murthy

BARIUM COMPOUNDS

Calcination

Crystal Structure

Polycrystalline materials

PREPARATION TEMPERATURE

Rietveld analysis

structure analysis

Ceramic materials

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

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

Crystallography Reports

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.

Materials Research Bulletin

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

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.

Materials Letters

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

The aim of this work is to understand the effect of the tilting of octahedra on polar phonon modes of lattice vibration, which contributes a major part to the dielectric polarization in the crystal. The tolerance factor, which is a measure of the packing of ions in the perovskite unit cell, determines the tilting of oxygen octahedra in the perovskite materials. In this work we have discussed the variation of polar phonon frequencies with respect to the tolerance factor in the composition (Ba(1-x)Srx)(Zn1/3Ta2/3)O3 with x = 0.0, 0.3, 0.5, 0.7, 1.0. The dielectric properties measured at the microwave frequency range are also highlighted to support the ideas proposed in this paper.

Physica B: Condensed Matter

Far-IR reflectance study on (Ba(1-x)Srx)(Zn1/3Ta2/3)O3 dielectric resonators as a function of tolerance factor

A new phase of Ba(Mg1/3Ta2/3)O3 has been obtained by calcination at 1400°C. It belongs to the cubic Pm3m with a = 4·08840 (4) A and the crystal structure has been found to be the ideal perovskite by the Rietveld method from powder X-ray diffraction data.

Fulltext

Bulletin of Materials Science

Crystal structure of Ba(Mg1/3Ta2/3)O3 calcinated at 1400°C

Journal of Korean Neurosurgical Society

Erratum to “Endoscopic Spine Surgery” by Choi G, et al. (J Korean Neurosurg Soc 60 : 485-497, 2017)

Journal of the American Ceramic Society

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

Journal	Crystallography Reports
ISSN	10637745
Open Access	No