Ruddleston - Popper phases

Many examples of Ruddleston-Popper phases have been synthesized. The structure of the first member of the series, corresponding to n = 1, is adopted by a number of compounds, including the important phase La2Cu04 (Section 4.3.3) and is often referred to as the K2NiF4 structure. In practice, synthesis of A +1B C)3 +i phases frequently results in disordered materials in which random or partly ordered regions of 100 faults occur, and particular efforts have to be made to produce perfectly ordered crystals. 

If the pair of A atoms at the boundaries of the perovskite-like sheets in the Ruddleston-Popper phases are replaced with just one A atom, the series of phases takes the formula A (A iB 03 +i), where A and A are large ions, typically a (+1/+3) pairing, and B is a medium-sized transition-metal ion, typically Nb5+. These materials are called Dion-Jacobson phases. The majority of examples synthesized to date are of the n = 2 phase, typified by KLaNb207, CsBiNb207, and so on (Fig. 4.29). A few examples of the n = 3 phase are also known, including CsCa2Nb3Oio-... 

Figure 4.28 Idealized structures of the Ruddleston-Popper phases Sr +1Ti 03 +i (a) Sr2Ti04, n = 1 (b) Sr3Ti207, n = 2 (c) Sr4Ti3O10, n = 3 and (d) SrTi03, n = oo. The shaded squares represent TiOg octahedra and the shaded circles Sr atoms.

Ruddleston-Popper phases and Aurivillius phases both contain slabs of structure similar to that of ... 

K2NiF4-related structures, also called Ruddleston-Popper phases, are built of slabs of perovskite structure cut parallel to the (idealized) perovskite 100 planes united by way of lamellae of halite (NaCl) structure. The series formula for these compounds is where A is a large cation,... 

Many other examples of Ruddleston-Popper phases have been synthesised. The generalised homologous series formula for these compounds Is fWl n03 + 1 [ = (A0)(AB03) or (H)(P) ] where A is a large cation, typically an alkali... 

K2NiF4-related structures, also called Ruddleston-Popper phases, are built of slabs of perovskite structure cut parallel to the (idealized) perovskite 100 planes united by way of lamellae of halite (NaCl) structure. The series formula for these compounds is A +iB 03 +i where A is a large cation, typically an alkali metal, alkaline earth or rare earth and B is a medium sized cation, typically a 3d transition metal cation. The first examples characterized were Sr2Ti04, Sr3Ti207 and Sr4Ti30g, in which the perovskite slabs are derived from SrTiOs and the halite slabs from SrO. 

Materials for Next Generation SOFCs relates two important strategies for improving fuel cell performance. The first section covers a nano-engineering solution, to produce thin layers to get surface (interfacial) ionic conductivity. The second section covers the use of new electrode materials based on Perovskite-related phases, Ruddleston-Popper phases, and double and triple perovskites. 

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