Effect of Zr doping on the microstructure and electric properties of BaHf0.1Ti0.9O3 ceramics

Pure and Zr-doped barium titanate hafnate (BaHf_0.1Ti_0.9O₃, short for BHT) ceramics were prepared by conventional solid state reaction method. The microstructures, dielectric and ferroelectric properties of BaHf_0.1Ti_0.9-x Zr _x O₃ (x = 0, 0.02, 0.04, 0.10) ceramics have been investigated. From the X-ray diffraction patterns it is indicated that Zr⁴⁺ ions have entered the unit cell maintaining the tetragonal perovskite structure of solid solution and the lattice constant of Zr-doped BHT ceramics increases with the increase of Zr content. There is an obvious difference between the grain shape of pure BHT ceramics and that of Zr-doped BHT ceramics. The temperature dependences of dielectric constant indicated that all of the three phase transition temperatures increase after doped zirconium. It is found that well-behaved hysteresis loops can be observed in pure and Zr-doped BHT ceramics. The remanent polarization (2P _r) and the coercive electric field (2E _C) of BaHf_0.1Ti_0.9-x Zr _x O₃ ceramics gradually decrease as the Zr content increases from 2 to 10 mol %.