| Abstract [eng] |
Ferroelectric phosphorous chalcogenide family investigated in this doctoral dissertation can be subdivided into two compounds groups. The first group is represented by the general formula M2P2X6 (where M - transition metal, X – chalcogenides), and can be classified as ternary phosphorus chalcogenides. The second crystal group is described by Van der Waals layered structure with the common chemical formula MIMIIIP2X6 (where MI, MIII – transition metals, X – chalcogenides). Most of these compounds are characterized by compact arrangement of chalcogen atoms, in which two atom layers of phosphorus and a layer of metal atoms placed between them construct the two-dimensional fragments in form of a sandwich. The main aim of this doctoral dissertation is to investigate the dielectric, ferroelectric, pyroelectric and noise properties related to the phase transitions of ternary and quaternary phosphorus chalcogenide crystals. The ferroelectric properties of the nominally pure ternary phosphorus chalcogenide Sn2P2S6 crystal has been investigated in this dissertation. The influence of various impurities on the dielectric, electrical and ferroelectric properties of the mixed crystals is also investigated. The copper indium thiophosphate (CuInP2S6) is the most prominent example of the quaternary phosphorus chalcogenides. Up till now, the structural and physical properties of CuInP2S6 bulk and nanoscale crystals have been extensively studied and reviewed. In this dissertation the low-frequency noise characteristics of the well-studied lamellar ferrielectric-semiconductor CuInP2S6 crystal were explored. |
