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Erschienen in:
17.02.2018
Effect of excess Bi on the structure and electrical properties of CaBi2Nb2O9 ultrahigh temperature piezoceramics
Erschienen in: Journal of Materials Science: Materials in Electronics | Ausgabe 9/2018
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Abstract
CaBi2Nb2O9 + x wt% Bi2O3 (x = 0, 1, 2, 3) ceramics with bismuth layer structure were prepared by solid state reaction route. The effect of excess bismuth on the crystal structure, microstructure and electrical properties of the ceramics was investigated. At all compositions, orthorhombic symmetric bismuth layer structure was formed without secondary phases. Excess bismuth caused more uniform grains. The ceramic with excess Bi2O3 of 1 wt% exhibited optimal electrical properties as follows: piezoelectric constant d33 = 6.4 pC/N, planar electromechanical coupling coefficient kp = 11.0%, dielectric constant \(\varepsilon _{{33}}^{T}/{\varepsilon _0}\) = 93.5, dielectric loss tanδ = 0.24%, and resistivity ρ = 2.9 × 106 Ω cm (@ 500 °C). This ceramic also possess ultrahigh Curie temperature Tc = 940 °C, indicating its potential application for high temperature sensors and actuators.