Tio Putra Wendari, Syukri Arief, Nandang Mufti, Andon Insani, Jacob Baas, Graeme R. Blake, Zulhadjri
Samples of PbBi2Nb2O9, PbBi1.5La0.5Nb2O9, and PbBi1.5Nd0.5Nb2O9 have been prepared by the molten salt method. The structure, morphology, and electrical properties were investigated. All samples are single-phase and crystallize in an orthorhombic structure with A21am symmetry. Neutron diffraction data indicate that the Ln3+ cations prefer to occupy the perovskite A-site, whereas Pb/Bi occupy the perovskite A-site and the Bi2O2 layer. Changes in unit cell volume are observed on substitution and are attributed to the ionic radii of the Ln3+ cations and also correlated to changes in the B-O bond distances in the BO6 octahedra, which are also observed in IR spectra. SEM images reveal anisotropic plate-like grains, which increase in size with the presence of Ln3+ ions. The ferroelectric transition temperature (Tc) decreases with decreasing degree of BO6 distortion as the influence of the 6s2 lone pair of Bi3+ is diminished. Relaxor ferroelectric behavior is observed with Ln3+ substitution, driven by the disorder of the A-site cations. The room temperature ferroelectric polarization increases with Ln3+ substitution, ascribed to the decreased dielectric loss. © 2020 Elsevier B.V.
Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Andalas, Kampus Limau, Manis, 25163, Padang, Indonesia; Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jl. Semarang 5, Malang, 65145, Indonesia; Center for Science and Technology of Advanced Materials, National Nuclear Energy Agency of Indonesia, Puspiptek Serpong, Tangerang Selatan, 15314, Indonesia; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, Netherlands
