The electrostrictive effect and dielectric properties of lead-free 0.5Ba(Zr_xTi_(1-x))O_3-0.5(Ba_(0.75)Ca_(0.25))TiO_3 ceramics

摘要

Lead-free 0.5Ba(Zr_xTi_(1-x))O_3-0.5(Ba_(0.75)Ca_(0.25))TiO_3 (x = 0.25, 0.30, 0.35, 0.40) ceramics have been synthesized by a conventional solid state sintering method. The room temperature ferroelectric and electrostrictive properties of these ceramics were studied. Based on the measured properties, these ceramics showed a typical relaxor behavior. The Curie temperature of BZT-BCT ceramics decreases with increasing the Zr content. The largest electrostrictive strain and electrostrictive coefficient are founded in BZT-BCT ceramic with x = 0.25, the value is 0.16 % and 0.079 m~4 C~(-2), respectively. The polarization, electrostrictive strain and electrostrictive coefficient (Q_(11)) decrease with increase in Zr concentration. For samples with low Curie temperature, which have large room temperature dielectric constant (ε), electrostrictive coefficient increases (Q_(11)) is smaller. Because doping can disrupt the long range cation order, and electrostrictive (Q_(11)) coefficient increases with cation order from disordered, through partially-ordered, simple relaxor and then ordered perovskites, ferroelectrics with a disordered structure have a huge permittivity, but a small electrostrictive coefficient (Q_(11)).