New Piezoceramic SrBi₂Nb_2-2WSnO₉: Crystal Structure, Microstructure and Dielectric Properties

By using the method of high-temperature solid-phase reaction, the new piezoceramic SrBi₂Nb_2-2WSnO₉ was obtained, where partial substitution of niobium (Nb) atoms with Sn⁴⁺ and W⁶⁺ atoms in the compound SrBi₂Nb₂O₉ occurred in the octahedra of the perovskite layer (B-position). X-ray diffraction investigations showed that these compounds are single-phase SrBi₂Nb_2-2WSnO₉ (x = 0.1, 0.2) and two-phase SrBi₂Nb_2-2WSnO₉ (x = 0.3, 0.4), but all of them had the structure of Aurivillius-Smolensky phases (ASPs) with close parameters of orthorhombic unit cells. It corresponded to the space group A21am. The temperature dependences of the relative permittivity ε/ε₀ and the tangent of the dielectric loss angle tan d were defined at various frequencies. It was found that doping SrBi₂Nb_2-2WSnO₉ (x = 0.1) improved the electrophysical properties of the compound: losses decreased, and the relative permittivity increased. This result was obtained for the first time. Moreover, a new result was obtained that indicated an improvement in the electrophysical properties of SrBi₂Nb₂O₉ using the chemical element Sn (tin). This refutes the previously existing opinion about the impossibility to use Sn as a doping element.