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Phase equilibria and electrical properties of pyrochlore and zirconolite phases in the Bi2O3-ZnO-Ta2O5 system.


Citation

Khaw, Chwin Chieh and Tan, Kar Ban and Lee, Chnoong Kheng and West, Anthony Roy (2012) Phase equilibria and electrical properties of pyrochlore and zirconolite phases in the Bi2O3-ZnO-Ta2O5 system. Journal of the European Ceramic Society, 32 (3). pp. 671-680. ISSN 0955-2219

Abstract / Synopsis

The complete subsolidus phase diagram of the system Bi2O3–ZnO–Ta2O5, including cubic pyrochlore and monoclinic zirconolite phases, has been determined at 950–1050 °C. Through systematic heat treatment and X-ray diffraction of over 100 compositions, the layout of compatibility triangles (both 2-phase and 3-phase) and single phase solid solution areas has been determined. Pyrochlore and zirconolite phases have ideal nominal compositions Bi1.5Zn1.0Ta1.5O7 and Bi2(Zn1/3Ta2/3)2O7 respectively, but both form solid solution areas. The sintering condition of pyrochlore pellets has been optimised to obtain high density ceramics with minimal weight loss: optimised condition is 1100 °C for pellets covered with sacrificial powder. Permittivity, ɛ′ dielectric loss and temperature coefficient of capacitance, TCC, of single phase materials were measured using impedance spectroscopy; ɛ′ and TCC show little variation with composition but the losses are higher for Zn-deficient compositions.


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Additional Metadata

Item Type: Article
Divisions: Faculty of Science
DOI Number: https://doi.org/10.1016/j.jeurceramsoc.2011.10.012
Publisher: Elsevier
Keywords: Powder solid-state reaction; Sintering; X-ray methods; Electrical properties.
Depositing User: Nur Farahin Ramli
Date Deposited: 21 Nov 2013 09:02
Last Modified: 21 Sep 2015 09:11
Altmetrics: http://www.altmetric.com/details.php?domain=psasir.upm.edu.my&doi=10.1016/j.jeurceramsoc.2011.10.012
URI: http://psasir.upm.edu.my/id/eprint/25293
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