期刊
MATERIALS
卷 15, 期 8, 页码 -出版社
MDPI
DOI: 10.3390/ma15082872
关键词
bismuth ferrite-barium titanate; niobium doping; non-linear dielectrics; lead-free piezoelectric; ferroelectric; relaxor ferroelectric; core-shell microstructure; energy storage capacitors
类别
资金
- Engineering and Physical Sciences Research Council [EP/S028978/1]
Niobium doping can improve the microstructure and dielectric properties of BF-BT ceramics, making the material suitable for energy storage capacitors and temperature-stable dielectrics.
BiFeO3-BaTiO3 (BF-BT) ceramics exhibit great potential for diverse applications in high temperature piezoelectric transducers, temperature-stable dielectrics and pulsed-power capacitors. Further optimization of functional properties for different types of applications can be achieved by modification of processing parameters or chemical composition. In the present work, the influence of pentavalent niobium substitution for trivalent ferric ions on the structure, microstructure and dielectric properties of 0.7BF-0.3BT ceramics was investigated systematically. Doping with niobium led to incremental reductions in grain size (from 7.0 to 1.3 mu m) and suppression of long-range ferroelectric ordering. It was found that core-shell type microstructural features became more prominent as the Nb concentration increased, which were correlated with the formation of distinct peaks in the dielectric permittivity-temperature relationship, at similar to 470 and 600 degrees C, which were attributed to the BT-rich shell and BF-rich core regions, respectively. Nb-doping of BF-BT ceramics yielded reduced electronic conductivity and dielectric loss, improved electrical breakdown strength and enhanced dielectric energy storage characteristics. These effects are attributed to the charge compensation of pentavalent Nb donor defects by bismuth vacancies, which suppresses the formation of oxygen vacancies and the associated electron hole conduction mechanism. The relatively high recoverable energy density (W-rec = 2.01 J cm(-3)) and energy storage efficiency (eta = 68%) of the 0.7BiFeO(3)-0.3BaTiO(3) binary system were achieved at 75 degrees C under an electric field of 15 kV mm(-1). This material demonstrates the greatest potential for applications in energy storage capacitors and temperature-stable dielectrics.
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