Liu Yunfei

Structure and electric properties of (1−x)(Bi1/2Na1/2) TiO3-xBaTiO3 Systems

The structural, dielectric and piezoelectric properties of (1−x)(Bi1/2Na1/2) TiO3-xBaTiO3 ceramics were investigated for the compositional range, x=0.02, 0.04, 0.06, 0.08, 0.10. The samples were synthesized by a conventional solid-state reaction technique. All compositions show a single perovskite structure, and X-ray powder diffraction patterns can be indexed using a rhombohedral structure. Lattice constants and lattice distortion increase while the amount of BaTiO3 increases. The X-ray diffraction results show the morphotropic phase boundary (MPB) of (1−x)(Bi1/2Na1/2) TiO3-xBaTiO exists in near x=0.06−0.08. Temperature dependence of dielectric constant ɛT33/ɛ0 measurement reveals that all compositions experience one structural phase and two ferroelectric phases transition below 400 °C: rhombohedral (or rhombohedral plus tetragonal) ferroelectric phase ↔ tetragonal antiferroelectric phase ↔ tetragonal paraelectric phase. Relaxor behaviors exist in the course of ferroelectric to antiferroelectric phase transition. Dielectric and piezoelectric properties are enhanced in the MPB range for (1−x)(Bi1/2Na1/2)TiO3-xBaTiO3.