Crystal structure and dielectric properties of Bi2O3-CaO-Nb2O5 compounds

Publication date: 15 February 2017
Source:Materials & Design, Volume 116
Author(s): Libin Gao, Ke Tang, Jiaming Xu, Zhengrui Xu
The Bi2O3-CaO-Nb2O5 (BCN) materials were prepared by solid-state reaction. The BCN pyrochlores exhibited a layered structure with general formula of CaBi2Nb2O9 when the sintering temperature below 1100°C, and the sample in a nearly pure phase at 1100°C. The structure of BCN ceramics was gradually transformed into Ca2Nb2O7 pyrochlore structure with further increasing the sintering temperature. The dielectric properties varied with structures. The BCN ceramic sintered at 1100°C exhibited excellent dielectric properties with a dielectric constant of ~110 and a dielectric loss of ~0.001. The dielectric constants of all the ceramics were independent with the measurement frequency (100Hz–1MHz) at room temperature. However, the dielectric loss decreased dramatically at low frequency and then increased slightly with increasing frequency. The temperature dependence of dielectric properties of BCN ceramics was also investigated. The BCN materials with a Ca2Nb2O7 pyrochlore structure were more sensitive to the temperature than that with a CaBi2Nb2O9 structure.

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