Perovskites hybridized with metal phases

DPMs can also be formulated as composite materials. In this concept, the contact of the two phases at the nanoscale provides materials with improved ionic and electronic conductivities. Examples of composite DPMs encompass the combination of two perovskite and fluorite phases for oxide ion conduction, the latter usually relying on the formula Cei >,Y >,02-5 (Y = Gd, Sm) [11-14]). Perovskites can also be hybridized with metal phases or cermets (most often based on Ni) for promoting the electronic conductivity and stability of cerates for H2 permeation [15-18]. Mass transfer within this membrane family can be described using either a unified permeation model for the two phases as for single-phase membranes or by including the contribution of each phase (Figure 14.2d). 

Perovskite layers can also be hybridized with metal phases or cermets (most often based on Ni) for promoting the electronic conductivity and stability of... 

Two factors combine to lend a greater diversity in the stereochemistries exhibited by bivalent germanium, tin and lead compounds, the increased radius of Mn compared with that of Mw and the presence of a non-bonding pair of electrons. When the non-bonding pair of electrons occupies the isotropic valence level s orbital, as in, for example, the complex cations Pb[SC(NH2)2]6+ and Pb[antipyrine]6+, or when they are donated to conductance band levels, as in the binary tin and lead selenides or tellurides or the perovskite ternary phases CsMX3 (M = Sn, Pb X = Cl, Br, I), then the metal coordination is regular. However, in the majority of compounds an apparent vacancy in the coordination sphere of the metal is observed, which is usually ascribed to the presence of the non-bonding pair of electrons in a hybrid orbital and cited as evidence for a stereochemically active lone pair . 

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