Novel monoclinic zirconolite in Bi2O3-CuO-Ta2O5 ternary system: Phase equilibria, structural and electrical properties

JOURNAL OF ALLOYS AND COMPOUNDS

卷:592

Article

Tan, K. B.¹  Chon, M. P.¹  Khaw, C. C.²  Zainal, Z.¹  Yap, Y. H. Taufiq¹  Tan, P. Y.¹ 

[1] Univ Putra Malaysia, Fac Sci, Dept Chem, Serdang 43400, Selangor, Malaysia

[2] Univ Tunku Abdul Rahman, Fac Sci & Engn, Dept Mech & Mat Engn, Kuala Lumpur 53300, Malaysia

关键词: Ceramics;    Solid state reaction;    Dielectric response;    ac Impedance spectroscopy;   

DOI  :  10.1016/j.jallcom.2013.11.197

来源: Elsevier

【 摘 要 】

Synthesis of novel monoclinic zirconolite, Bi1.92Cu0.08(Cu0.3Ta0.7)(2)O-7.06 (beta-BCT) using solid state reaction had been finalised at the firing temperature of 900 degrees C over 24 h. The X-ray diffraction pattern of beta-BCT was fully indexed on a monoclinic symmetry, space group, C2/c with lattice constants, a = 13.1052 (8), b = 7.6749 (5), c = 12.162 (6), alpha = gamma = 90 degrees and beta = 101.32 degrees (1), respectively. The reaction mechanism study indicated phase formation was greatly influenced by the reaction between intermediate bismuth tantalate binary phases and CuO at elevated temperatures. beta-BCT was thermally stable up to a temperature of 900 degrees C and contained spherulite grains with sizes ranging from 1 to 14 mu m. Electrical properties of this material were characterised over a broad temperature range covering temperatures from 10 K to 874 K. At the temperature of 304 K, two semicircles were discernible in complex Cole-Cole plot showing an insulating grain boundary with C-gb = 6.63 10 (9) F cm (1) and a bulk response capacitance, C-b = 6.74 x 10 (12) F cm (1). The Power law frequency-dependent ac conductivity of beta-BCT was apparent in three frequency regimes; a low-frequency plateau regime, a high-frequency plateau regime and a dispersive regime taking place in the temperature range of 220-576 K. The frequency-dependent ac conductivity of beta-BCT with increasing temperature was attributed to the thermal activated electrical conduction mechanism within the structure. (C) 2014 Published by Elsevier B.V.

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