SnTiO3 MATERIAL, METHOD OF PREPARATION THEREOF, USE THEREOF AS FERROELECTRIC MATERIAL AND DEVICE COMPRISING A FERROELECTRIC MATERIAL

摘要

The present invention relates to a material of the formula SnTiO₃ having a crystal structure comprised of layers, wherein the layers comprise Sn(II) ions, Ti(IV) ions and edge-sharing O₆-octahedra, the edge-sharing O₆-octahedra form a sub-layer, the Ti(IV) ions are located within ⅔ of the edge-sharing O₆-octahedra, thus forming edge-sharing TiO₆-octahedra, the edge-sharing TiO₆-octahedra form a honeycomb structure within the sub-layer, the honeycomb structure comprising hexagons with Ti(IV)-vacancies within the hexagons, the Sn(II) ions are located above and below the Ti(IV)-vacancies with respect to the sub-layer, the Ti(IV) ions are optionally substituted with M, M is one or more elements selected from Group 4 and Group 14 elements, and the crystal structure satisfies at least one of the following features (i) and (ii): (i) the Sn(II) ions have a tetrahedral coordination sphere involving three O ions of the layer and the electron lone pair of the Sn(II) ions which is situated at an apical position relative to the three O ions of the layer, (ii) the layers are stacked so that each layer is translated relative to each adjacent layer by a stacking vector S1 or a stacking vector S2, the centers of adjacent hexagons form a parallelogram with a side having a length x and side having a length y, the stacking vector S1 is a combined translation along the side having the length x by ⅔ x and along the side having a lengthy by ⅓ y, the stacking vector S2 is a combined translation along the side having the length x by ⅓ x and along the side having a lengthy by ⅔ y, and the crystal structure comprises layers translated relative to adjacent layers by the stacking vector 1 and layers translated relative to adjacent layers by the stacking vector S2. The present invention is further directed to a material of the formula SnTiO₃ having a tetragonal perovskite-type crystal structure, a method for the preparation of SnTiO₃, a device comprising a ferroelectric material and a use of the material of the formula SnTiO₃ in a ferroelectric element.