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

The structural, dielectric and piezoelectric properties of (1-x)(Bi^sub 1/2^Na^sub 1/2^) TiO^sub 3^-xBaTiO^sub 3^ 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 BaTiO^sub 3^ increases. The X-ray diffraction results show the morphotropic phase boundary (MPB) of (1-x)(Bi^sub 1/2^Na^sub 1/2^) TiO^sub 3^-xBaTiO exists in near x=0.06-0.08. Temperature dependence of dielectric constant ^sup T^ ^sub 33^/ ^sub 0^ 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)(Bi^sub 1/2^Na^sub 1/2^)TiO^sub 3^-xBaTiO^sub 3^.[PUBLICATION ABSTRACT]