TY - JOUR

T1 - Dielectric performance of pyrochlore-type Bi2MgNb2-xTaxO9 ceramics

T2 - The effects of tantalum doping

AU - Zhuk, N. A.

AU - Krzhizhanovskaya, M. G.

AU - Sekushin, N. A.

AU - Kharton, V. V.

AU - Makeev, B. A.

AU - Belyy, V. A.

AU - Korolev, R. I.

N1 - Publisher Copyright: © 2021 Elsevier Ltd and Techna Group S.r.l. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/7/15

Y1 - 2021/7/15

N2 - The solid solutions based on the pyrochlore-type system Bi2MgNb2-xTaxO9 were formed in the compositional range х = 0–2.0 (Bi1·6Mg0·8Nb1.6-tTatO7.2, t = 0–1.6). The Rietveld method was used to refine the structure for Bi2MgNb2-xTaxO9 (x = 0, 1.0, 2.0). The increasing tantalum content led to the slight decrease in the cubic unit cell parameters from 10.56934 (4) Å for x = 0 and 10.54607 (3) Å for x = 2 (sp.gr. Fd-3m:2). At the same time, tantalum additions suppressed grain growth in the pyrochlore ceramics during sintering and made it possible to obtain materials with an average grain size of 1–2 μm (Bi1·6Mg0·8Ta1·6O7.2). The increase in the Ta5+ concentration led to the decrease in the dielectric permeability from 104 (Bi1·6Mg0·8Nb1·6O7.2) to 20 (Bi1·6Mg0·8Ta1·6O7.2) at room temperature, while the dielectric loss tangent remained lower than 0.002, which is due to the small grain size and the high porosity of the samples. An increase in temperature has practically no effect on the values of the dielectric permittivity in the entire frequency range. The samples have weak through conductivity. The activation energies of electrical conductivity varied in the range of 0.84–1.00 eV, and the less tantalum, the lower the activation energy. The electrical properties of the samples at 200 Hz to 1 MHz are described by the simplest parallel scheme.

AB - The solid solutions based on the pyrochlore-type system Bi2MgNb2-xTaxO9 were formed in the compositional range х = 0–2.0 (Bi1·6Mg0·8Nb1.6-tTatO7.2, t = 0–1.6). The Rietveld method was used to refine the structure for Bi2MgNb2-xTaxO9 (x = 0, 1.0, 2.0). The increasing tantalum content led to the slight decrease in the cubic unit cell parameters from 10.56934 (4) Å for x = 0 and 10.54607 (3) Å for x = 2 (sp.gr. Fd-3m:2). At the same time, tantalum additions suppressed grain growth in the pyrochlore ceramics during sintering and made it possible to obtain materials with an average grain size of 1–2 μm (Bi1·6Mg0·8Ta1·6O7.2). The increase in the Ta5+ concentration led to the decrease in the dielectric permeability from 104 (Bi1·6Mg0·8Nb1·6O7.2) to 20 (Bi1·6Mg0·8Ta1·6O7.2) at room temperature, while the dielectric loss tangent remained lower than 0.002, which is due to the small grain size and the high porosity of the samples. An increase in temperature has practically no effect on the values of the dielectric permittivity in the entire frequency range. The samples have weak through conductivity. The activation energies of electrical conductivity varied in the range of 0.84–1.00 eV, and the less tantalum, the lower the activation energy. The electrical properties of the samples at 200 Hz to 1 MHz are described by the simplest parallel scheme.

KW - Bismuth niobate

KW - Bismuth tantalate

KW - Ceramics

KW - Dielectric properties

KW - Microstructure

KW - Pyrochlore

KW - SUBSOLIDUS PHASE-EQUILIBRIA

KW - ELECTRICAL-PROPERTIES

KW - OPTICAL-PROPERTIES

UR - http://www.scopus.com/inward/record.url?scp=85103727573&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/d0ee9eeb-a5b1-36e8-bce1-20d7bd741f28/

U2 - 10.1016/j.ceramint.2021.03.279

DO - 10.1016/j.ceramint.2021.03.279

M3 - Article

AN - SCOPUS:85103727573

VL - 47

SP - 19424

EP - 19433

JO - Ceramics International

JF - Ceramics International

SN - 0272-8842

IS - 14

ER -