Ruddlesden-Popper-type compounds

Figure 13.14 The crystal structures of the n = 2andn = 3 (R,AU,Cu 02n+2+6 Ruddlesden-Popper type compounds...

Compounds Containing Perovsldte Layers. A second class of layered oxides have structures related to the three-dimensional perovsldte lattice and include the Auriv-iUius phases, the Ruddlesden Popper phases and the Dion-Jacobson phases. The general composition can be written M [A iB 03 +i] where A is an alkaline or rare earth metal, and B is niobium or titanium. In the AurivUhus phases M = Bi202 +, whereas M is an aUcah metal cation in the ion-exchangeable Ruddlesden Popper a = 2) and Dion-Jacobson a = 1) phases. The relationships between the three structure types is shown in Figure 14. The intercalation chemistry of the Dion Jacobson phases was the first to be studied. 

Perovskite-type layered compounds are the intergrowth of perovskite l ers (P) ABO3 and slabs of the differ type of structure (rock salt, calcium fluorite type, cations of metals). Depending on the nature of slabs between perovskite blocks, layered compounds belong to three big groups Ruddlesden-Popper phases, Aurivillius phases, Dion-Jacobson phases. 

Thus, today Ruddlesden-Popper phases include complex oxides eontaining metals from groups 1,2, 13, 14 and 15 as well as transition (d- and 4f-) elements. The general formula of such oxides can be written as A0(AB03)n, where A means alkaline, alkali earth or rare earth element, while B is d-element, Al, Ga, In, Pb or Bi. This formula shows the main structural feature of this class of the layered perovskite-like eompoimds, that is the intergrowth of the perovskite blocks AMO3 (P) and rock salt blocks AO (RS) in a consequence -Pn-RS-Pn-RS-. In case of n = 00 the perovskite structure itself is obtained. Pigure 1 shows schematically the structure of the Ruddlesden-Popper phases (n=3) as eompared to the other types of the layered perovskite-like compounds. 

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