Investigation on the design and synthesis of new systems of BNT-based lead-free piezoelectric ceramics
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Three primary differences between BNT- and PZT-based ceramics were analyzed from the composition and the active component of the materials. Based on the analysis the authors’ group developed the new idea of the design of the multiple complex in the A-site ions of BNT compounds. (Bi0.5Na0.5)2+, Bi3+ and Na+ in the ABO3 structure are defined as A-site, A1-site and A2-site ions, respectively, and A, A1 and A2-site ions can be simultaneously or singly substituted partially by alkaline-earth metal ions, metal ions with +3 valence and metal ions with +1 valence, respectively. Under this consideration, Several new systems of Bi0.5Na0.5TiO3 (abbreviated as BNT)-based lead-free piezoelectric ceramics were proposed. These ceramics can be prepared by conventional ceramic techniques and have excellent piezoelectric performance. Among these materials, Bi0.5(Na1−x−yKxLiy)0.5TiO3 possesses higher piezoelectric constant (d33 = 230 pC/N), higher electromechanical couple factor (kp = 0.40), larger remanent polarization (Pr = 38.9 μC/cm2) and a better P-E hysteresis loop until about 200∘C.
KeywordsBi0.5(Na1−x−yKxLiy)0.5TiO3 Lead-free piezoelectric ceramics Piezoelectric constants Electromechanical couple factor Remanent polarization
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