Sr4 + n Mn3 + 4Mn4 + nO10 + 3n : a new homologous series of oxygen-vacancy-ordered perovskites from Mn3 + O5 pyramids and Mn4+O6 octahedra

CUPRATOS

PEROVSKITAS

2008

BIBLIOGRAFÍA NACIONAL QUÍMICA

A new homologous series of oxygen-vacancy-ordered perovskites with the formula Sr_{4+n}Mn^{3+}_4Mn^{4+}_nO_{10+3n} is proposed based on the structural trends found for the recently described Sr4Mn4O10, Sr5Mn5O13 and Sr7Mn7O19 compounds. These compounds correspond to n = 0 (Sr4Mn^{3+}_4O10), n = 1 (Sr5Mn^{3+}_4Mn4+O13) and n = 3 (Sr7Mn^{3+}_4Mn^{4+}_3O19) members of the series. A linear set of four Mn3+O5 pyramids placed on the ab plane and pointing along the +x, -y, +y, -x directions defines the n = 0 building block for the series. The nth members can be constructed from blocks containing four pyramids and n Mn4+O6 octahedra with 2/m symmetry. Compounds in the related systems CaMnOx and LaCuOx, containing Mn3+ and Cu2+ pyramids and Mn4+ and Cu3+ octahedra have also been found to be members of the series. The size and charge of the A-site cation and the apical distortion of the pyramidally coordinated B-site cation are shown to be important factors in the stabilization of certain members of the series. A qualitative explanation for the absence of some of the possible members of the series is presented based on these factors.

Acta Crystallographica Section B: Structural Science v. 64, no. 2, 2008. -- p.177-186

International Union of Crystallography

2008

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doi:10.1107/S0108768108002760