Dielectric, ferroelectric, and piezoelectric properties of (Na 0.47 Bi 0.47 Ba 0.06 ) 1−x Sr x TiO 3 lead-free ceramics with different mean radii of the A-site cations

The ceramics (Na 0.47 Bi 0.47 Ba 0.06 ) 1−x Sr x TiO 3 were prepared by means of a solid-state sintering method. Effects of Sr 2+ -doping on microstructure, ferroelectric, impedance, dielectric, and piezoelectric properties of the ceramics were investigated. Variation of electrical properties of the ceramics with the change of the mean radii of the A-site cations was shown. All ceramics exhibit dense microstructures and pure perovskite structure. Dielectric behavior is related to the electric poling and Sr 2+ amount. Compared to the ceramic with x = 0, the values of coercive field of the ceramics with x = 0.03 and 0.05 decrease from 34.7 to 27.6 kV/cm and 20.4 kV/cm, respectively; the corresponding remnant polarization values increase from 28.5 to 32.8 μC/cm 2 and 31.2 μC/cm 2 , respectively. The ceramics with x = 0, 0.01, 0.02, 0.03, 0.05, and 0.08 exhibit the piezoelectric constant (d 33 ) values of 119, 123, 138, 169, 187, and 91 pC/N, respectively. With the increase of annealing temperature, the samples with x = 0.01, 0.02, and 0.03 show good temperature stability of d 33 .