High pressure synthesis, lattice distortion, and dielectric properties of a perovskite Bi(Ni1/2Ti1/2)O3

A perovskite Bi(Ni1/2Ti1/2)O-3 was successfully synthesized under high pressure 6 GPa. This compound has orthorhombric cell with the parameters, a = 2a(m)sin(beta/2) = 0.5626(2) nm, b = 4b(m) = 1.5681(6) nm, and c = 2c(m)cos(beta/2) 0.5548(2) nm containing eight monoclinic primitive perovskite unit with the parameters, a(m) = c(m) = 0.39507(7) nm, b(m) = 0.39203(15), and beta = 90.80(2)degrees, and the lattice distortion is expected to be antiferroelectric. In addition, the sudden increase in the dielectric constant accompanied by the anomaly of dielectric loss was observed at 490 K as the temperature increases. This is though to correspond to the transition from antiferroelectric phase to another one.