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, e{open}' dielectric loss and temperature coefficient of capacitance, TCC, of single phase materials were measured using impedance spectroscopy; e{open}' and TCC show little variation with composition but the losses are higher for Zn-deficient compositions. © 2011 Elsevier Ltd.
CITATION STYLE
Khaw, C. C., Tan, K. B., Lee, C. K., & West, A. R. (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), 671–680. https://doi.org/10.1016/j.jeurceramsoc.2011.10.012
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