Abstract
(1xy)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3–yBiFeO3 (BNKFT-x/y with 0.12rxr0.24, 0ryr0.07) lead-free piezoelectric ceramics
have been prepared by the combustion technique. The effects of amounts of x and y on structures and electrical properties were
examined. Powders and ceramics can be well calcined and sintered at 750 1C for 2 h and 1025–1050 1C, respectively. The results
indicated that the crystalline structure and microstructure changed with the increase of x and y concentrations. XRD results of BNKFTx/0.03
and BNKFT-0.18/y ceramics with 0.12rxr0.24 and 0ryr0.07 showed the rhombohedral–tetragonal morphotropic phase
boundary (MPB). The addition of y caused a promoted grain growth while the addition of x suppressed the grain growth. The highest
density (r¼5.85 g/cm3
), superior dielectric properties at Tc (er¼7846 and tan d¼0.02), remnant polarization measured at 40 kV/cm
(Pr ¼ 20.1 mC/cm2
) and piezoelectric coefficient (d33¼213 pC/N) were obtained for x¼0.18 and y¼0.03.
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