Phase transition and piezoelectric, ferromagnetic response of B-site (Co, Nb) modified BaTiO3 ceramics

Structure, phase transformation and electric properties of BaTi1-x(Co1/2Nb1/2)(x)O-3 (0.01 <= x <= 0.10) ceramics were investigated. Results showed that the compositions with 0.02 < x < 0.07 contained both orthorhombic and tetragonal phases at room temperature. As the substitution level increased, the evolution of dielectric properties from a sharp ferroelectric peak to a round dielectric peak with pinched phase transitions was observed, accompanying the increased diffuseness. When the substitution level increased up to 0.07, the coexistence of ferroelectric and ferromagnetic behavior was found. Due to the different possible polarization states resulting from the coexistence of orthorhombic and tetragonal phases, the composition with x=0.05 exhibited the following optimum piezoelectric properties: d(33)*=272 pm/V, d(33)=195, and k(p)=32%. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.