Perovskite periodic table, metallic elements

More than 90% of the natural metallic elements of the periodic table form perovskites the wide range of cations, the possibility of partial substitution of A or B cation sites, and the remarkable capacity to accommodate a multitude of different kinds of defects result in a wealth of properties of these solids leading to applications ranging from superconductors (33) to oxidation catalysts (34). 

The extensive variety of properties that these compounds show is derived from the fact that around 90% of the metallic natural elements of the periodic table are known to be stable in a perovskite-type oxide structure [74], Besides, the possibility of synthesizing multicomponent perovskites by partial substitution of cations in positions A and B gives rise to substituted compounds with a formula A, A B,. B 03 ft. The resulting materials can be catalysts, insulators, semiconductors, superconductors, or ionic conductors. 

Many ternary oxides with compositions of A B O3, A B O3, A B O3, A +B + 03, and an abundance of compounds with more complex compositions, are crystallized in perovskite structure. The perovskite structure is very flexible, allowing not only the substitution of different cations in positions A and B over a wide range of compositions Ai xA xBi xBx03, but also the introduction of vacancies or substitutions on the anion sublattice. It is for this reason that about 90% of the metallic elements of the Periodic Table are known to be stable in a perovskite-type oxide structure. 

Approximately 90% of the metallic elements of the Periodic Table are known to form stable oxides with the perovskite structure. Further, it is possible to partially substitute A and B cations to yield a perovskite of the formula Ai xA xBi-yB y03. 

Oxides form the most common and interesting compounds with perovskite structure. Almost all the metallic natural elements in the periodic table are found in stable perovskites. Also, materials with this structure can be obtained by partial substitution of one or more metallic elements in the A site and/or in the B site. The wide range of properties shown by perovskite-type oxides find applications in catalysis, magnetism, solid oxide fuel cells, and superconductivity. Proper combination or partial substitution of the A site and/or B site atoms introduces abnormal valences or lattice defects, which in turn gives rise to interesting changes in their properties. 

The larger A cations, usually alkaline or rare earth elements, with inert d" or f electronic structure, act as structural stabilizers and do not offer much to the redox catalytic activity. The smaller B cations can be 3d, 4d, or 5d transition metal elements and are the main catalytic sites/centers in such solids due to their ability to undergo reversed redox cycles without destruction of the structure. In the vast majority of catalytic studies, 3d cations are employed due to obvious economic reasons. Nevertheless, almost 95% of the elements of the periodic table can participate in perovskites and these many possible combinations result in a plethora of diverse, and sometimes imexpected, properties of such solids, which have been nick-named chemical chameleons. 

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