Phase Transitions in Incipient Ferroelectrics of Perovskite Structure with Impurities

摘要: The name perovskite has been dated back to 1839 when Rose, a Russian mineralogist, discovered new mineral CaTiO3, which he baptized after the then Minister of Lands, count L.A.Perovsky. This later used designate large ABO3 family. A lot well-known classical ferroelectrics belong this Two members family, SrTiO3 and KTaO3, have polar soft mode, but do not exhibit ferroelectric phase transition similar 4He quantum liquid in crystalline state never realized at normal pressure. is explained by stabilization their paraelectric fluctuations [1,2]. So KTaO3 are paraelectrics or incipient ferroelectrics. They may be, certain sense, classified as marginal systems limit stability. Small perturbations can destroy stability induce phase. For example, becomes low temperatures under action an uniaxial stress only 1 kbar [3,4] application static electric fields kV/cm [5, 6, 7]. means that elastic lattice strains about 104 order 10-5 atomic sufficient It appeares [8,9] impurities with concentration around 10-3 also Just effect various on transitions will be discussed present paper. main attention paid CaTiO3 shortly discussed.